Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			$ (172,054)	$ (85,143)
Unrealized holding losses, net, before tax			(280,918)	(43,732)
Foreign currency translation adjustment, before tax			(7,873)	881
Unrealized losses on cash flow hedges			(174,371)	(5,969)
Total other comprehensive income (loss) before reclassifications, before tax			(463,162)	(48,820)
Amortization of unrealized holding losses on held-to-maturity securities			1,765	2,232
Gains realized in net income				(4)
Accretion of net gain on terminated cash flow hedges, before tax			(60)	(60)
Net yield adjustment from cash flow hedges currently in effect, before tax			(57,966)	(148,655)
Amortization of prior service credit, before tax			(1,128)	(2,093)
Amortization of actuarial losses, before tax			9,206	43,862
Total other comprehensive income (loss), before tax			(511,345)	(153,538)
Ending balance, before tax	$ (683,399)	$ (238,681)	(683,399)	(238,681)
Beginning balance, tax			44,476	22,111
Unrealized holding losses, net, tax			72,691	11,596
Foreign currency translation adjustment, tax			1,961	(188)
Unrealized [losses] on cash flow hedges			45,129	1,565
Total other comprehensive income (loss) before reclassifications, tax			119,781	12,973
Amortization of unrealized holding losses on held-to-maturity securities, tax			(456)	(587)
Gains realized in net income, tax				1
Accretion of net gain on terminated cash flow hedges, tax			17	17
Net yield adjustment from cash flow hedges currently in effect, tax			15,002	38,965
Amortization of prior service credit, tax			267	590
Amortization of actuarial losses, tax			(2,178)	(12,363)
Total other comprehensive income (loss), tax			132,433	39,596
Ending balance, tax	176,909	61,707	176,909	61,707
Beginning balance, net of tax			(127,578)	(63,032)
Unrealized holding losses, net of tax			(208,227)	(32,136)
Foreign currency translation adjustments	(4,264)	145	(5,912)	693
Unrealized losses on cash flow hedges, net of tax			(129,242)	(4,404)
Total other comprehensive income (loss) before reclassifications, net of tax			(343,381)	(35,847)
Amortization of unrealized holding losses on held-to-maturity securities			1,309	1,645
Gains realized in net income, net of tax				(3)
Accretion of net gain on terminated cash flow hedges, net of tax			(43)	(43)
Net yield adjustment from cash flow hedges currently in effect, net of tax			(42,964)	(109,690)
Amortization of prior service credit, net of tax			(861)	(1,503)
Amortization of actuarial losses, net of tax			7,028	31,499
Total other comprehensive income (loss)	(129,105)	(38,496)	(378,912)	(113,942)
Ending balance, net of tax	(506,490)	(176,974)	(506,490)	(176,974)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			104,691	195,386
Unrealized holding losses, net, before tax			(280,918)	(43,732)
Total other comprehensive income (loss) before reclassifications, before tax			(280,918)	(43,732)
Amortization of unrealized holding losses on held-to-maturity securities			1,765	2,232
Gains realized in net income				(4)
Total other comprehensive income (loss), before tax			(279,153)	(41,504)
Ending balance, before tax	(174,462)	153,882	(174,462)	153,882
Total other comprehensive income (loss)			(206,918)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			(360,276)	(650,087)
Amortization of prior service credit, before tax			(1,128)	(2,093)
Amortization of actuarial losses, before tax			9,206	43,862
Total other comprehensive income (loss), before tax			8,078	41,769
Ending balance, before tax	(352,198)	(608,318)	(352,198)	(608,318)
Total other comprehensive income (loss)			6,167
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax			83,531	369,558
Foreign currency translation adjustment, before tax			(7,873)	881
Unrealized losses on cash flow hedges			(174,371)	(5,969)
Total other comprehensive income (loss) before reclassifications, before tax			(182,244)	(5,088)
Accretion of net gain on terminated cash flow hedges, before tax			(60)	(60)
Net yield adjustment from cash flow hedges currently in effect, before tax			(57,966)	(148,655)
Total other comprehensive income (loss), before tax			(240,270)	(153,803)
Ending balance, before tax	$ (156,739)	$ 215,755	$ (156,739)	$ 215,755