Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Consolidated Statements of Comprehensive Income
Net income	$ 41,460	$ 40,459	$ 85,827	$ 82,785
Unrealized gains (losses) on securities:
Unrealized holding gains (losses) arising during period	24,593	(8,216)	42,426	(30,298)
Tax effect	(5,410)	1,807	(9,334)	6,697
Reclassification adjustment for gains included in net income	(1,709)	641	(2,250)	641
Tax effect	376	(141)	496	(141)
Net of tax amount	17,850	(5,909)	31,338	(23,101)
Unrealized gains (losses) on derivative financial instruments qualifying as cash flow hedges:
Unrealized holding gains (losses) arising during period	(11,275)	8	(13,943)	44
Tax effect	2,480	(2)	3,067	(10)
Reclassification adjustment for gains (losses) included in interest expense	(350)	39	(343)	87
Tax effect	77	(8)	75	(19)
Net of tax amount	(9,068)	37	(11,144)	102
Change in pension plan obligation:
Reclassification adjustment for changes included in net income	7,767	194	7,888	387
Tax effect	(1,709)	(43)	(1,735)	(85)
Net of tax amount	6,058	151	6,153	302
Other comprehensive income (loss), net of tax	14,840	(5,721)	26,347	(22,697)
Comprehensive income	$ 56,300	$ 34,738	$ 112,174	$ 60,088