Accumulated Other Comprehensive Income (Loss) - Reclassifications out of AOCI - (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Reclassifications out of accumulated other comprehensive income, net of tax
Interest expense	$ (3,624)	$ (2,213)
Other noninterest income	1,674	1,365
Provision for income taxes	(7,103)	(12,562)
Net income	18,264	24,494
Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Net income	185	95
Gains and Losses on Cash Flow Hedges | Amount Reclassified from Accumulated Other Comprehensive Loss | Interest rate contracts
Reclassifications out of accumulated other comprehensive income, net of tax
Interest expense	110	73
Provision for income taxes	(42)	(28)
Net income	68	45
Unrealized gain and losses on sales of available for sale securities | Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Other noninterest income		(122)
Provision for income taxes		46
Net income		(76)
Benefit plans | Amount Reclassified from Accumulated Other Comprehensive Loss
Reclassifications out of accumulated other comprehensive income, net of tax
Salaries and employee benefits	188	204
Provision for income taxes	(71)	(78)
Net income	$ 117	$ 126