Loan Servicing Rights - LSRs Activity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	$ 64,701	$ 68,837	$ 71,013	$ 63,841
Additions from loans sold with servicing retained	2,109	2,284	4,242	4,251
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(695)	(727)	(1,494)	(1,450)
Changes in estimates of fair value	(5,457)	(30)	(13,103)	3,722
Fair value, end of period	60,658	70,364	60,658	70,364
Principal balance of loans serviced	6,775,213	6,988,846	6,775,213	6,988,846
Commercial Real Estate
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	559	441	451	427
Additions from loans sold with servicing retained	0	45	138	88
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(34)	(29)	(64)	(58)
Changes in estimates of fair value	0	0	0	0
Fair value, end of period	525	457	525	457
Principal balance of loans serviced	43,657	42,490	43,657	42,490
Mortgage
Activity for loan servicing rights and the related fair value changes
Fair value, beginning of period	64,142	68,396	70,562	63,414
Additions from loans sold with servicing retained	2,109	2,239	4,104	4,163
Changes in fair value due to:
Reductions from pay-offs, pay downs and run-off	(661)	(698)	(1,430)	(1,392)
Changes in estimates of fair value	(5,457)	(30)	(13,103)	3,722
Fair value, end of period	60,133	69,907	60,133	69,907
Principal balance of loans serviced	$ 6,731,556	$ 6,946,356	$ 6,731,556	$ 6,946,356