VIEs - Low Income Housing Tax Credit Partnership (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Low Income Housing Tax Credit Partnerships
Variable Interest Entity [Line Items]
Affordable housing tax credit investments	$ 870,421		$ 877,237
Less: amortization	(310,602)		(300,357)
Net affordable housing tax credit investments	559,819		576,880
Unfunded commitments	279,270		$ 292,721
Tax credits and other tax benefits recognized	23,283	$ 18,285
Proportional Amortization Method
Variable Interest Entity [Line Items]
Tax credit amortization expense included in provision for income taxes	16,961	12,407
Equity Method
Variable Interest Entity [Line Items]
Tax credit investment (gains) losses included in non-interest income	$ 109	$ 132