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Component: (Network and Table)
Network
2402404 - Disclosure - Summary of significant accounting policies (Change in warranty liability) (Details)
(http://www.f-e-t.com/role/SummaryOfSignificantAccountingPoliciesChangeInWarrantyLiabilityDetails)
Table(Implied)
Slicers (applies to each fact value in each table cell)
Reporting Entity [Axis]0001401257 (http://www.sec.gov/CIK)
Accounting Policies [Abstract]Period [Axis]
2016-01-01 - 2016-12-31
2015-01-01 - 2015-12-31
2014-01-01 - 2014-12-31
Accounting Policies [Abstract]
 
 
 
Movement in Standard and Extended Product Warranty, Increase (Decrease) [Roll Forward]
 
 
 
Balance at beginning of period
5,697,000  
5,314,000  
5,280,000  
Charged to expense
4,031,000  
5,539,000  
2,588,000  
Deductions or other
(6,504,000) 
(5,156,000) 
(2,554,000) 
Balance at end of period
3,224,000  
 
5,697,000  
 
5,314,000