CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 76,468	$ 72,802	$ 189,798	$ 114,767
Unrealized gains and losses on available for sale securities
Net gains (losses) arising during the period	18,488	(6,249)	34,755	(27,446)
Less reclassification adjustment for net (gains) losses included in net income	(8)	42	18	574
Total	18,480	(6,207)	34,773	(26,872)
Unrealized gains and losses on derivatives (cash flow hedges)
Net (losses) gains on derivatives arising during the period	(683)	455	(1,065)	2,415
Less reclassification adjustment for net losses included in net income	274	619	482	1,655
Total	(409)	1,074	(583)	4,070
Defined benefit pension plan
Amortization of net loss	55	112	110	224
Total other comprehensive income (loss)	18,126	(5,021)	34,300	(22,578)
Total comprehensive income	$ 94,594	$ 67,781	$ 224,098	$ 92,189