Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 31,823	$ 24,516	$ 50,087	$ 49,010
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	1,803	4,631	6,920	16,551
Tax effect	(688)	(1,766)	(2,638)	(6,311)
Reclassification adjustment for (gains) losses included in net income	(110)		(110)	(122)
Tax effect	43		42	46
Net of tax amount	1,048	2,865	4,214	10,164
Unrealized losses on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding losses arising during period	18	(46)	(60)	(198)
Tax effect	(7)	18	23	75
Reclassification adjustment for losses included in interest expense	19	68	168	142
Tax effect	(7)	(26)	(64)	(54)
Net of tax amount	23	14	67	(35)
Change in pension plan obligation:
Reclassification adjustment for changes included in net income	187	204	376	408
Tax effect	(71)	(78)	(143)	(156)
Net of tax amount	116	126	233	252
Other comprehensive income (loss), net of tax	1,187	3,005	4,514	10,381
Comprehensive income	$ 33,010	$ 27,521	$ 54,601	$ 59,391