Fair Value of Assets and Liabilities - Reconciliation of Assets with Unobservable Inputs (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 9,362	$ 6,859	$ 8,178	$ 5,294
Change included in earnings	(720)	(150)	(1,146)	(184)
Purchases and issuances	6,612	4,996	11,056	8,938
Sales and settlements	(5,104)	(4,540)	(7,938)	(6,883)
Ending balance	10,150	7,165	10,150	7,165
Net change in unrealized gains (losses) relating to items held at end of period	1,417	1,337	1,417	1,337
Mortgage servicing rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	8,039	5,325	7,305	4,157
Change included in earnings	(118)	(48)	(144)	234
Purchases and issuances	812	551	1,572	1,437
Sales and settlements	0	0	0	0
Ending balance	8,733	5,828	8,733	5,828
Net change in unrealized gains (losses) relating to items held at end of period	0	0	0	0
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	1,323	1,534	873	1,137
Change included in earnings	(602)	(102)	(1,002)	(418)
Purchases and issuances	5,800	4,445	9,484	7,501
Sales and settlements	(5,104)	(4,540)	(7,938)	(6,883)
Ending balance	1,417	1,337	1,417	1,337
Net change in unrealized gains (losses) relating to items held at end of period	$ 1,417	$ 1,337	$ 1,417	$ 1,337