CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 87,268	$ 113,330
Unrealized gains and losses on available for sale securities
Net gains arising during the period	26,068	16,267
Less reclassification adjustment for net losses included in net income	27	26
Total	26,095	16,293
Unrealized gains and losses on derivatives (cash flow hedges)
Net losses on derivatives arising during the period	(1,057)	(382)
Less reclassification adjustment for net losses included in net income	438	208
Total	(619)	(174)
Defined benefit pension plan
Amortization of actuarial net loss	172	55
Total other comprehensive income	25,648	16,174
Total comprehensive income	$ 112,916	$ 129,504