CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 95,601	$ 76,468	$ 182,869	$ 189,798
Unrealized gains and losses on available for sale securities
Net gains arising during the period	3,013	18,488	29,081	34,755
Less reclassification adjustment for net losses (gains) included in net income	31	(8)	58	18
Total	3,044	18,480	29,139	34,773
Unrealized gains and losses on derivatives (cash flow hedges)
Net losses on derivatives arising during the period	(1,280)	(683)	(2,337)	(1,065)
Less reclassification adjustment for net (gains) losses included in net income	(308)	274	130	482
Total	(1,588)	(409)	(2,207)	(583)
Defined benefit pension plan
Amortization of actuarial net loss	172	55	344	110
Total other comprehensive income	1,628	18,126	27,276	34,300
Total comprehensive income	$ 97,229	$ 94,594	$ 210,145	$ 224,098