Fair Value, Assets Measured on Recurring Basis [Table Text Block] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Investment securities available for sale: | | | | | | | | | | | | | | | | | | | $ | - | | | $ | 106,142 | | | $ | - | | | $ | 106,142 | | Residential mortgage backed securities | | | - | | | | 326,239 | | | | - | | | | 326,239 | | | | | - | | | | 95,930 | | | | - | | | | 95,930 | | | | | - | | | | 8,079 | | | | 1,500 | | | | 9,579 | | | | | - | | | | - | | | | 218 | | | | 218 | | | | | - | | | | 51,629 | | | | - | | | | 51,629 | | Mortgage banking derivatives | | | - | | | | - | | | | 114 | | | | 114 | | Total assets measured at fair value on a recurring basis as of December 31, 2016 | | $ | - | | | $ | 588,019 | | | $ | 1,832 | | | $ | 589,851 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mortgage banking derivatives | | $ | - | | | $ | - | | | $ | 55 | | | $ | 55 | | Interest rate swap derivatives | | | - | | | | 692 | | | | - | | | | 692 | | Total liabilities measured at fair value on a recurring basis as of December 31, 2016 | | $ | - | | | $ | 692 | | | $ | 55 | | | $ | 747 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Investment securities available for sale: | | | | | | | | | | | | | | | | | | | $ | - | | | $ | 56,975 | | | $ | - | | | $ | 56,975 | | Residential mortgage backed securities | | | - | | | | 297,241 | | | | - | | | | 297,241 | | | | | - | | | | 118,381 | | | | - | | | | 118,381 | | | | | - | | | | 14,938 | | | | - | | | | 14,938 | | | | | 115 | | | | - | | | | 219 | | | | 334 | | | | | - | | | | 47,492 | | | | - | | | | 47,492 | | Mortgage banking derivatives | | | - | | | | - | | | | 24 | | | | 24 | | Total assets measured at fair value on a recurring basis as of December 31, 2015 | | $ | 115 | | | $ | 535,027 | | | $ | 243 | | | $ | 535,385 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mortgage banking derivatives | | $ | - | | | $ | - | | | $ | 30 | | | $ | 30 | | Interest rate swap derivatives | | | - | | | | 1,417 | | | | - | | | | 1,417 | | Total liabilities measured at fair value on a recurring basis as of December 31, 2015 | | $ | - | | | $ | 1,417 | | | $ | 30 | | | $ | 1,447 | | |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Beginning balance at January 1, 2016 | | $ | 219 | | | $ | 24 | | | $ | 243 | | Realized gain (loss) included in earnings - net mortgage banking derivatives | | | - | | | | 90 | | | | 90 | | Purchases of available-for-sale securities | | | 1,500 | | | | - | | | | 1,500 | | | | | (1 | ) | | | - | | | | (1 | ) | Ending balance at December 31, 2016 | | $ | 1,718 | | | $ | 114 | | | $ | 1,832 | | | | | | | | | | | | | | | | | | | | | | | | | | | | Beginning balance at January 1, 2016 | | $ | - | | | $ | 30 | | | $ | 30 | | Realized loss (gain) included in earnings - net mortgage banking derivatives | | | - | | | | 25 | | | | 25 | | | | | - | | | | - | | | | - | | Ending balance at December 31, 2016 | | $ | - | | | $ | 55 | | | $ | 55 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Beginning balance at January 1, 2015 | | $ | 219 | | | $ | 146 | | | $ | 365 | | Realized (loss) gain included in earnings - net mortgage banking derivatives | | | - | | | | (122 | ) | | | (122 | ) | | | | - | | | | - | | | | - | | Ending balance at December 31, 2015 | | $ | 219 | | | $ | 24 | | | $ | 243 | | | | | | | | | | | | | | | | | | | | | | | | | | | | Beginning balance at January 1, 2015 | | $ | - | | | $ | 250 | | | $ | 250 | | Realized (gain) loss included in earnings - net mortgage banking derivatives | | | - | | | | (220 | ) | | | (220 | ) | | | | - | | | | - | | | | - | | Ending balance at December 31, 2015 | | $ | - | | | $ | 30 | | | $ | 30 | | |
Fair Value Measurements, Nonrecurring [Table Text Block] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ | - | | | $ | - | | | $ | 2,956 | | | $ | 2,956 | | Income producing - commercial real estate | | | - | | | | - | | | | 12,993 | | | | 12,993 | | Owner occupied - commercial real estate | | | - | | | | - | | | | 2,133 | | | | 2,133 | | Real estate mortgage - residential | | | - | | | | - | | | | 555 | | | | 555 | | Construction - commercial and residential | | | - | | | | - | | | | 1,550 | | | | 1,550 | | | | | - | | | | - | | | | 13 | | | | 13 | | | | | - | | | | - | | | | 2,694 | | | | 2,694 | | Total assets measured at fair value on a nonrecurring basis as of December 31, 2016 | | $ | - | | | $ | - | | | $ | 22,894 | | | $ | 22,894 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ | - | | | $ | - | | | $ | 2,633 | | | $ | 2,633 | | Income producing - commercial real estate | | | - | | | | - | | | | 10,088 | | | | 10,088 | | Owner occupied - commercial real estate | | | - | | | | - | | | | 1,353 | | | | 1,353 | | Real estate mortgage - residential | | | - | | | | - | | | | 329 | | | | 329 | | Construction - commercial and residential | | | - | | | | - | | | | 4,627 | | | | 4,627 | | | | | - | | | | - | | | | 123 | | | | 123 | | | | | - | | | | - | | | | 20 | | | | 20 | | | | | - | | | | - | | | | 5,852 | | | | 5,852 | | Total assets measured at fair value on a nonrecurring basis as of December 31, 2015 | | $ | - | | | $ | - | | | $ | 25,025 | | | $ | 25,025 | | |
Fair Value, by Balance Sheet Grouping [Table Text Block] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ | 10,285 | | | $ | 10,285 | | | $ | - | | | $ | 10,285 | | | $ | - | | | | | 2,397 | | | | 2,397 | | | | - | | | | 2,397 | | | | - | | Interest bearing deposits with other banks | | | 355,481 | | | | 355,481 | | | | - | | | | 355,481 | | | | - | | | | | 538,108 | | | | 538,108 | | | | - | | | | 536,390 | | | | 1,718 | | Federal Reserve and Federal Home Loan Bank stock | | | 21,600 | | | | 21,600 | | | | - | | | | 21,600 | | | | - | | | | | 51,629 | | | | 51,629 | | | | - | | | | 51,629 | | | | - | | | | | 5,677,893 | | | | 5,683,158 | | | | - | | | | - | | | | 5,683,158 | | Bank owned life insurance | | | 60,130 | | | | 60,130 | | | | - | | | | 60,130 | | | | - | | | | | 11,929 | | | | 11,929 | | | | - | | | | 11,929 | | | | - | | Mortgage banking derivatives | | | 114 | | | | 114 | | | | - | | | | - | | | | 114 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Noninterest bearing deposits | | | 1,775,684 | | | | 1,775,684 | | | | - | | | | 1,775,684 | | | | - | | Interest bearing deposits | | | 3,191,682 | | | | 3,191,682 | | | | - | | | | 3,191,682 | | | | - | | | | | 748,748 | | | | 745,985 | | | | - | | | | 745,985 | | | | - | | Customer repurchase agreements | | | 68,876 | | | | 68,876 | | | | - | | | | 68,876 | | | | - | | | | | 216,514 | | | | 203,657 | | | | - | | | | 203,657 | | | | - | | Mortgage banking derivatives | | | 55 | | | | 55 | | | | - | | | | - | | | | 55 | | Interst rate swap derivatives | | | 692 | | | | 692 | | | | - | | | | 692 | | | | - | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | $ | 10,270 | | | $ | 10,270 | | | $ | - | | | $ | 10,270 | | | $ | - | | | | | 3,791 | | | | 3,791 | | | | - | | | | 3,791 | | | | - | | Interest bearing deposits with other banks | | | 284,302 | | | | 284,302 | | | | - | | | | 284,302 | | | | - | | | | | 487,869 | | | | 487,869 | | | | 115 | | | | 487,535 | | | | 219 | | Federal Reserve and Federal Home Loan Bank stock | | | 16,903 | | | | 16,903 | | | | - | | | | 16,903 | | | | - | | | | | 47,492 | | | | 47,492 | | | | - | | | | 47,492 | | | | - | | | | | 4,998,368 | | | | 5,000,717 | | | | - | | | | - | | | | 5,000,717 | | Bank owned life insurance | | | 58,682 | | | | 58,682 | | | | - | | | | 58,682 | | | | - | | | | | 12,136 | | | | 12,136 | | | | - | | | | 12,136 | | | | - | | Mortgage banking derivatives | | | 24 | | | | 24 | | | | - | | | | - | | | | 24 | | Interest rate swap derivatives | | | - | | | | - | | | | - | | | | - | | | | - | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Noninterest bearing deposits | | | 1,405,067 | | | | 1,405,067 | | | | - | | | | 1,405,067 | | | | - | | Interest bearing deposits | | | 3,014,122 | | | | 3,014,122 | | | | - | | | | 3,014,122 | | | | - | | | | | 739,255 | | | | 736,973 | | | | - | | | | 736,973 | | | | - | | Customer repurchase agreements | | | 72,356 | | | | 72,356 | | | | - | | | | 72,356 | | | | - | | | | | 70,000 | | | | 69,992 | | | | - | | | | 69,992 | | | | - | | Mortgage banking derivatives | | | 30 | | | | 30 | | | | - | | | | - | | | | 30 | | Interest rate swap derivatives | | | 1,417 | | | | 1,417 | | | | - | | | | 1,417 | | | | - | | |