Accumulated Other Comprehensive Income (Loss) - Changes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Pre-tax Amount
Other comprehensive income (loss), Pre-tax Amount	$ 37,607	$ (539,801)
Income Tax Benefit (Expense)
Other comprehensive income (loss), Income Tax Benefit (Expense)	(10,032)	143,992
Net of tax
Balance	2,269,005	2,656,912
Other comprehensive income (loss)	27,575	(395,809)
Balance	2,329,012	2,285,149
Accumulated Other Comprehensive Income (Loss)
Pre-tax Amount
Accumulated other comprehensive income (loss), beginning balance, Pre-tax Amount	(871,813)	(165,967)
Accumulated other comprehensive (loss) income, ending balance, Pre-tax Amount	(834,206)	(705,768)
Income Tax Benefit (Expense)
Accumulated other comprehensive income (loss), beginning balance, Income Tax Benefit (Expense)	232,559	44,274
Accumulated other comprehensive loss, ending balance, Income Tax Benefit (Expense)	222,527	188,266
Net of tax
Balance	(639,254)	(121,693)
Other comprehensive income (loss)	27,575	(395,809)
Balance	(611,679)	(517,502)
Pensions and Other Benefits
Net of tax
Balance	(5,431)	(24,390)
Balance	(5,431)	(24,390)
Investment securities
Pre-tax Amount
Unrealized net gains (losses) arising during the period, Pre-tax Amount	25,038	(538,085)
Reclassification of net losses (gains) to net income, Pre-tax Amount	(11,708)
Other comprehensive income (loss), Pre-tax Amount	36,746	(538,085)
Income Tax Benefit (Expense)
Unrealized net losses (gains) arising during the period, Income Tax Benefit (Expense)	(6,679)	143,534
Reclassification of net gains (losses) to net income, Income Tax Benefit (Expense)	(3,123)
Other comprehensive income (loss), Income Tax Benefit (Expense)	(9,802)	143,534
Net of tax
Unrealized net (losses) gains arising during the period, Net of tax	18,359	(394,551)
Reclassification of net (gains) losses to net income, Net of tax	(8,585)
Other comprehensive income (loss)	26,944	(394,551)
Cash Flow Derivative Hedges
Pre-tax Amount
Unrealized net gains (losses) arising during the period, Pre-tax Amount	(442)	(1,716)
Reclassification of net losses (gains) to net income, Pre-tax Amount	1,303
Other comprehensive income (loss), Pre-tax Amount	861	(1,716)
Income Tax Benefit (Expense)
Unrealized net losses (gains) arising during the period, Income Tax Benefit (Expense)	118	458
Reclassification of net gains (losses) to net income, Income Tax Benefit (Expense)	348
Other comprehensive income (loss), Income Tax Benefit (Expense)	(230)	458
Net of tax
Balance	(4,702)
Unrealized net (losses) gains arising during the period, Net of tax	(324)	(1,258)
Reclassification of net (gains) losses to net income, Net of tax	955
Other comprehensive income (loss)	631	(1,258)
Balance	$ (4,071)	$ (1,258)