Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement of Comprehensive Income [Abstract]
Net income	$ 40,063	$ 29,992	$ 138,838	$ 52,130
Securities available for sale:
Unrealized holding (losses) gains on securities	(9,250)	388	(20,491)	19,685
Reclassification adjustment for gains realized in net income	(570)	0	(1,582)	(23)
Total securities available for sale	(9,820)	388	(22,073)	19,662
Derivative instruments:
Unrealized holding gains (losses) on derivative instruments	1,215	1,175	7,551	(2,621)
Total derivative instruments	1,215	1,175	7,551	(2,621)
Defined benefit pension and post-retirement benefit plans:
Amortization of net actuarial loss recognized in net periodic pension cost	49	48	148	145
Total defined benefit pension and post-retirement benefit plans	49	48	148	145
Other comprehensive (loss) income, net of tax	(8,556)	1,611	(14,374)	17,186
Comprehensive income	$ 31,507	$ 31,603	$ 124,464	$ 69,316