Fair Value (Changes Level 3 assets (fair value, recurring)) (Details) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Purchases, acquired, sales and settlements:
Gains included in net gains on sale of loans held for sale	$ 11,968	$ 23,938
Interest rate lock commitments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	2,790	3,168	$ 3,168
Total gains (losses):
Included in earnings	(587)		(1,564)
Issuances	1,580		5,373
Purchases, acquired, sales and settlements:
Settlements	(1,320)		(4,187)
Balance at period end	2,463		2,790
Gains included in net gains on sale of loans held for sale	2,500		2,800
Z-TRANCHE Securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	2,224	$ 2,039	2,039
Total gains (losses):
Included in earnings	2,810		0
Included in other comprehensive income	(2,166)		185
Purchases, acquired, sales and settlements:
Purchases	0		0
Sales	(2,868)		0
Settlements	0		0
Balance at period end	$ 0		$ 2,224