Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 18,264	$ 24,494
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	5,116	11,920
Tax effect	(1,950)	(4,545)
Reclassification adjustment for (gains) losses included in net income		(122)
Tax effect		46
Net of tax amount	3,166	7,299
Unrealized losses on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding losses arising during period	(38)	(152)
Tax effect	14	58
Reclassification adjustment for losses included in interest expense	110	73
Tax effect	(42)	(28)
Net of tax amount	44	(49)
Change in pension plan obligation:
Reclassification adjustment for changes included in net income	188	204
Tax effect	(71)	(78)
Net of tax amount	117	126
Other comprehensive income (loss), net of tax	3,327	7,376
Comprehensive income	$ 21,591	$ 31,870