Mortgage Servicing Rights (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Data and key economic assumptions related to mortgage servicing rights
Unpaid principal balance	$ 2,763,344	$ 3,090,839	$ 1,178,390
Weighted-average prepayment speed (CPR) (percent)	7.34%	8.89%	8.25%
Estimated impact of a 10% increase	$ (1,034)	$ (1,203)	$ (1,038)
Estimated impact of a 20% increase	$ (2,010)	$ (2,330)	$ (1,441)
Discount rate (percent)	9.64%	9.51%	10.76%
Estimated impact of a 100bp increase	$ (1,368)	$ (1,357)	$ (1,010)
Estimated impact of a 200bp increase	$ (2,629)	$ (2,612)	$ (1,378)
Weighted-average coupon interest rate (percent)	3.83%	3.97%	3.84%
Weighted-average servicing fee (basis points)	0.2587%	0.2504%	0.2504%
Weighted-average remaining maturity (in years)	11 years 1 month 11 days	15 years 2 months 23 days	24 years 4 months 29 days