Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Deferred tax assets
Allowance for loan and lease losses	$ 50,172	$ 50,123
Deferred compensation	8,320	8,166
Other real estate owned	8,309	8,380
Interest rate swap agreements	5,705	7,554
Acquisition fair market value adjustments	4,763	5,842
Net operating loss carryforwards	4,737	3,590
Employee benefits	3,927	3,165
Other	5,569	5,433
Total gross deferred tax assets	91,502	92,253
Deferred tax liabilities
Deferred loan costs	(8,061)	(7,427)
Intangibles	(5,477)	(6,272)
FHLB stock dividends	(3,976)	(4,601)
Depreciation of premises and equipment	(3,111)	(2,376)
Available-for-sale securities	(1,036)	(8,812)
Other	(2,720)	(4,290)
Total gross deferred tax liabilities	(24,381)	(33,778)
Net deferred tax asset	$ 67,121	$ 58,475