CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net change in Unrealized (losses) gains, tax (benefit) expense	$ (21,972)	$ 14,538
Reclassification adjustment for gains, tax expense	79	166
Amortization of unrealized gain on securities reclassified to held-to-maturity, tax expense	5	21
Change in unfunded pension liability related to unrealized (loss) gain, prior service cost and transition obligation, tax (benefit) expense	(5)	1
Reclassification adjustment related to derivatives, tax benefit (expense)	0	501
Amortization of unrealized gain on terminated cash flow hedges, tax expense	(35)	0
Equity method investment tax benefit	$ (86)	$ 0