Accumulated Other Comprehensive Loss - Changes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Pre-tax Amount
Other comprehensive income (loss), Pre-tax Amount	$ (119,057)	$ (43,316)	$ (732,442)	$ (126,923)
Income Tax Benefit (Expense)
Other comprehensive income (loss), Income Tax Benefit (Expense)	31,758	11,555	195,379	33,856
Net of tax
Balance	2,252,611	2,731,341	2,656,912	2,744,104
Other comprehensive loss	(87,299)	(31,761)	(537,063)	(93,067)
Balance	2,200,651	2,711,734	2,200,651	2,711,734
Accumulated Other Comprehensive Income (Loss)
Pre-tax Amount
Accumulated other comprehensive income (loss), beginning balance, Pre-tax Amount	(779,352)	(40,509)	(165,967)	43,098
Accumulated other comprehensive (loss) income, ending balance, Pre-tax Amount	(898,409)	(83,825)	(898,409)	(83,825)
Income Tax Benefit (Expense)
Accumulated other comprehensive income (loss), beginning balance, Income Tax Benefit (Expense)	207,895	10,807	44,274	(11,494)
Accumulated other comprehensive loss, ending balance, Income Tax Benefit (Expense)	239,653	22,362	239,653	22,362
Net of tax
Balance	(571,457)	(29,702)	(121,693)	31,604
Other comprehensive loss	(87,299)	(31,761)	(537,063)	(93,067)
Balance	(658,756)	(61,463)	(658,756)	(61,463)
Pensions and Other Benefits
Net of tax
Balance	(24,390)	(31,737)	(24,390)	(31,737)
Balance	(24,390)	(31,737)	(24,390)	(31,737)
Investment Securities
Pre-tax Amount
Reclassification of net losses (gains) to net income, Pre-tax Amount	15,217		35,146
Other comprehensive income (loss), Pre-tax Amount		(43,316)		(126,923)
Income Tax Benefit (Expense)
Reclassification of net gains (losses) to net income, Income Tax Benefit (Expense)	(4,058)		(9,375)
Other comprehensive income (loss), Income Tax Benefit (Expense)		11,555	193,205	33,856
Net of tax
Balance	(220,021)	2,035	(97,303)	63,341
Reclassification of net (gains) losses to net income, Net of tax	11,159		25,771
Other comprehensive loss	(95,323)	(31,761)	(556,857)	(93,067)
Balance	(281,741)	(29,726)	(281,741)	(29,726)
Investment securities: Unrealized net losses arising during the period
Pre-tax Amount
Unrealized net gains (losses) arising during the period, Pre-tax Amount	(130,000)	(43,316)	(759,437)	(126,821)
Income Tax Benefit (Expense)
Unrealized net losses (gains) arising during the period, Income Tax Benefit (Expense)	34,677	11,555	202,580	33,829
Net of tax
Unrealized net (losses) gains arising during the period, Net of tax	(95,323)	$ (31,761)	(556,857)	(92,992)
Investment securities: Investment securities gains, net
Pre-tax Amount
Reclassification of net losses (gains) to net income, Pre-tax Amount				(102)
Income Tax Benefit (Expense)
Reclassification of net gains (losses) to net income, Income Tax Benefit (Expense)				27
Net of tax
Reclassification of net (gains) losses to net income, Net of tax				$ (75)
Investment Securities (including reclassification of net losses to net income)
Pre-tax Amount
Other comprehensive income (loss), Pre-tax Amount	(114,783)		(724,291)
Income Tax Benefit (Expense)
Other comprehensive income (loss), Income Tax Benefit (Expense)	30,619
Net of tax
Other comprehensive loss	(84,164)		(531,086)
Cash Flow Derivative Hedges
Pre-tax Amount
Unrealized net gains (losses) arising during the period, Pre-tax Amount	(4,372)		(7,611)
Reclassification of net losses (gains) to net income, Pre-tax Amount	98		(540)
Other comprehensive income (loss), Pre-tax Amount	(4,274)		(8,151)
Income Tax Benefit (Expense)
Unrealized net losses (gains) arising during the period, Income Tax Benefit (Expense)	1,165		2,030
Reclassification of net gains (losses) to net income, Income Tax Benefit (Expense)	26		(144)
Other comprehensive income (loss), Income Tax Benefit (Expense)	1,139		2,174
Net of tax
Balance	(2,842)
Unrealized net (losses) gains arising during the period, Net of tax	(3,207)		(5,581)
Reclassification of net (gains) losses to net income, Net of tax	72		(396)
Other comprehensive loss	(3,135)		(5,977)
Balance	$ (5,977)		$ (5,977)