CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 81,891	$ 69,559	$ 271,689	$ 184,326
Unrealized gains and losses on available for sale securities
Net gains (losses) arising during the period	8,135	(8,683)	42,890	(36,129)
Less reclassification adjustment for net losses included in net income	72	57	90	631
Total	8,207	(8,626)	42,980	(35,498)
Unrealized gains and losses on derivatives (cash flow hedges)
Net gains (losses) on derivatives arising during the period	76	221	(989)	2,636
Less reclassification adjustment for net losses included in net income	324	472	806	2,127
Total	400	693	(183)	4,763
Defined benefit pension plan
Amortization of net loss	56	113	166	337
Total other comprehensive income (loss)	8,663	(7,820)	42,963	(30,398)
Total comprehensive income	$ 90,554	$ 61,739	$ 314,652	$ 153,928