| Goodwill and Intangible Assets Disclosure [Abstract] | Period [Axis] |
|---|
2016-01-01 - 2016-12-31 |
|---|
Goodwill and Intangible Assets Disclosure [Abstract] | |
Schedule of Business Acquisitions, by Acquisition [Table Text Block] | A summary of the preliminary purchase price allocation and resulting goodwill follows (in thousands): | | | | | Cash and cash equivalents | $ | 166,215 |
| Securities | 14,431 |
| Loans1 | 444,482 |
| Premises and equipments, net | 8,035 |
| Intangible assets – Core deposit premium | 6,510 |
| Other assets | 3,599 |
| Total assets acquired | 643,272 |
| | | Deposits | 598,735 |
| Other borrowings | 7,217 |
| Other liabilities | 980 |
| Total liabilities assumed | 606,932 |
| | | Net assets acquired | 36,340 |
| Less: purchase price | 102,500 |
| Goodwill | $ | 66,160 |
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1 Loans are presented net of participations sold to BOKF NA. |
Schedule of Finite-Lived Intangible Assets [Table Text Block] | The following table presents the original cost and accumulated amortization of intangible assets (in thousands): | | | | | | | | | | | | Dec. 31, | | | 2016 | | 2015 | Core deposit premiums | | $ | 35,879 |
| | $ | 29,369 |
| Less accumulated amortization | | 29,369 |
| | 29,101 |
| Net core deposit premiums | | 6,510 |
| | 268 |
| | | | | | Other identifiable intangible assets | | 60,951 |
| | 55,509 |
| Less accumulated amortization | | 20,530 |
| | 11,868 |
| Net other identifiable intangible assets | | 40,421 |
| | 43,641 |
| | | | | | Total intangible assets, net | | $ | 46,931 |
| | $ | 43,909 |
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Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] | Expected amortization expense for intangible assets that will continue to be amortized (in thousands): | | | | | | | | | | | | | | | | Core Deposit Premiums | | Other Identifiable Intangible Assets | | Total | 2017 | | $ | 808 |
| | $ | 4,565 |
| | $ | 5,373 |
| 2018 | | 732 |
| | 3,908 |
| | 4,640 |
| 2019 | | 716 |
| | 3,556 |
| | 4,272 |
| 2020 | | 697 |
| | 3,420 |
| | 4,117 |
| 2021 | | 675 |
| | 3,063 |
| | 3,738 |
| Thereafter | | 2,882 |
| | 21,909 |
| | 24,791 |
| | | $ | 6,510 |
| | $ | 40,421 |
| | $ | 46,931 |
|
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Schedule of Goodwill [Table Text Block] | The changes in the carrying value of goodwill by operating segment are as follows (in thousands): | | | | | | | | | | | | | | | | | | | | | | | | Commercial Banking | | Consumer Banking | | Wealth Management | | Funds Management and Other | | Total | Balance, December 31, 2014 | | | | | | | | | | | Goodwill | | $ | 269,363 |
| | $ | 39,251 |
| | $ | 69,394 |
| | $ | — |
| | $ | 378,008 |
| Accumulated impairment losses | | — |
| | (228 | ) | | — |
| | — |
| | (228 | ) | | | 269,363 |
| | 39,023 |
| | 69,394 |
| | — |
| | 377,780 |
| | | | | | | | | | | | Goodwill acquired during 2015 | | 7,681 |
| | — |
| | — |
| | — |
| | 7,681 |
| | | | | | | | | | | | Balance, December 31, 2015 | | | | | | | | | | | Goodwill | | 277,044 |
| | 39,251 |
| | 69,394 |
| | — |
| | 385,689 |
| Accumulated impairment losses | | — |
| | (228 | ) | | — |
| | — |
| | (228 | ) | | | 277,044 |
| | 39,023 |
| | 69,394 |
| | — |
| | 385,461 |
| | | | | | | | | | | | Goodwill acquired during 2016 | | 1,210 |
| | — |
| | 2,126 |
| | 66,160 |
| | 69,496 |
| Adjustment1 | | (6,058 | ) | | — |
| | — |
| | — |
| | (6,058 | ) | | | | | | | | | | | | Balance, December 31, 2016 | | | | | | | | | | | Goodwill | | 272,196 |
| | 39,251 |
| | 71,520 |
| | 66,160 |
| | 449,127 |
| Accumulated impairment losses | | — |
| | (228 | ) | | — |
| | — |
| | (228 | ) | | | $ | 272,196 |
| | $ | 39,023 |
| | $ | 71,520 |
| | $ | 66,160 |
| | $ | 448,899 |
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| | 1 | Completion of an external audit of Heartland Food Products resulted in a reallocation of the purchase price between net assets acquired, intangible assets and goodwill during 2016. |
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