Mortgage Servicing Rights - Schedule of Servicing Income and Expense Included in Mortgage Banking Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Servicing income:
Servicing income	$ 3,463	$ 3,661	$ 8,958	$ 8,312
Change in fair value of mortgage servicing rights	(1,383)		(3,724)
Change in fair value of mortgage servicing rights hedging instruments	490		490
Gross servicing income	2,570	3,661	5,724	8,312
Servicing expenses:
Servicing asset amortization		2,796		6,221
Servicing asset impairment		2,402		8,089
Loss on sale of mortgage servicing rights			249
Other servicing expenses	1,043	686	3,181	1,632
Gross servicing expenses	1,043	5,884	3,430	15,942
Net servicing income (loss)	$ 1,527	$ (2,223)	$ 2,294	$ (7,630)