Other Assets - Changes in Amortized MSRs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Changes in amortized mortgage servicing rights
Balance at beginning of year	$ 21,435	$ 25,191
Originations	65	1,786
Amortization	(4,691)	(5,542)	$ (3,900)
Balance at end of year	16,809	21,435	25,191
Fair value of amortized MSRs at end of year	25,160	29,676
Balance of loans serviced for others	2,702,489	3,220,865
Impairment of MSRs recorded	$ 0	$ 0	$ 0