Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income	$ 27,143	$ 31,399	$ 56,384	$ 86,682
Unrealized gains and losses on available for sale debt securities:
Net unrealized (losses) gains arising during the period	(428)	2,614	15,388	19,854
Reclassification adjustment for gains included in net income	0	0	0	0
Total	(428)	2,614	15,388	19,854
Unrealized gains (losses) on derivatives	880	137	(6,117)	(813)
Amortization related to post-retirement obligations	85	35	239	57
Total other comprehensive income	537	2,786	9,510	19,098
Total comprehensive income	$ 27,680	$ 34,185	$ 65,894	$ 105,780