Fair Value of Assets and Liabilities - Reconciliation of Assets with Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 8,178	$ 5,294
Change included in earnings	(426)	(34)
Purchases and issuances	4,444	3,942
Sales and settlements	(2,834)	(2,343)
Ending balance	9,362	6,859
Net change in unrealized gains (losses) relating to items held at end of period	1,323	1,534
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	7,305	4,157
Change included in earnings	(26)	282
Purchases and issuances	760	886
Sales and settlements	0	0
Ending balance	8,039	5,325
Net change in unrealized gains (losses) relating to items held at end of period	0	0
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	873	1,137
Change included in earnings	(400)	(316)
Purchases and issuances	3,684	3,056
Sales and settlements	(2,834)	(2,343)
Ending balance	1,323	1,534
Net change in unrealized gains (losses) relating to items held at end of period	$ 1,323	$ 1,534