Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement of Comprehensive Income [Abstract]
Net income	$ 74,262	$ 94,301
Investment securities AFS
Net unrealized (losses)	(103,284)	(23,979)
Net unrealized (losses) on AFS securities transferred to HTM securities	(67,604)	0
Amortization of net unrealized losses on AFS securities transferred to HTM securities	1,108	518
Reclassification adjustment for net losses (gains) realized in net income	(21)	39
Income tax benefit	43,098	5,851
Other comprehensive (loss) on AFS securities	(126,702)	(17,571)
Defined benefit pension and postretirement obligations
Amortization of prior service cost	(81)	(37)
Amortization of actuarial loss	74	1,050
Income tax (expense) benefit	2	(253)
Other comprehensive income (loss) on pension and postretirement obligations	(6)	760
Total other comprehensive (loss)	(126,708)	(16,811)
Comprehensive income (loss)	$ (52,445)	$ 77,490