Comprehensive Income - Components of Other Comprehensive Income (Loss) and Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) to Net Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (85,143)	$ (279,959)	$ (569,328)
Unrealized holding gains (losses), net, before tax	(95,114)	141,081	247,411
Foreign currency translation adjustment, before tax	(1,218)	2,724	1,381
Unrealized gain (losses) on cash flow hedges	(32,292)	505,042	160,373
Current year benefit plans gains (loss), before tax	206,274	(238,218)	(126,618)
Total other comprehensive income (loss) before reclassifications, before tax	77,650	410,629	282,547
Amortization of unrealized holding losses on held-to-maturity securities	4,427	3,606	3,394
Gains (losses) realized in net income	(8)	(2)	3
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(120)	(125)	(136)
Net yield adjustment from cash flow hedges currently in effect, before tax	(252,397)	(271,971)	(13,011)
Amortization of prior service credit, before tax	(4,185)	(4,181)	(4,173)
Amortization of actuarial losses, before tax	87,722	56,860	20,745
Total other comprehensive income (loss), before tax	(86,911)	194,816	289,369
Ending balance, before tax	(172,054)	(85,143)	(279,959)
Beginning balance, tax	22,111	73,279	149,247
Unrealized holding gains (losses), net, tax	24,870	(36,498)	(65,009)
Foreign currency translation adjustment, tax	356	(440)	(290)
Unrealized gain (losses) on cash flow hedges	8,410	(130,432)	(42,163)
Current year benefit plans gains (loss),tax	54,016	(60,208)	(33,287)
Total other comprehensive income (loss) before reclassifications, tax	(20,380)	(107,162)	(74,175)
Amortization of unrealized holding losses on held-to-maturity securities, tax	(1,154)	(966)	(892)
Gains (losses) realized in net income, tax	2	1	(1)
Accretion of net gain (losses) on terminated cash flow hedges, tax	32	34	36
Net yield adjustment from cash flow hedges currently in effect, tax	65,741	70,239	3,421
Amortization of prior service credit, tax	1,095	1,057	1,097
Amortization of actuarial losses, tax	(22,971)	(14,371)	(5,454)
Total other comprehensive income (loss), tax	22,365	(51,168)	(75,968)
Ending balance, tax	44,476	22,111	73,279
Current year benefit plans gains loss, tax	(54,016)	60,208	33,287
Beginning balance, net of tax	(63,032)	(206,680)	(420,081)
Unrealized holding gains (losses), net of tax	(70,244)	104,583	182,402
Foreign currency translation adjustments	(862)	2,284	1,091
Unrealized gain (losses) on cash flow hedges net of tax	(23,882)	374,610	118,210
Current year benefit plans gains (losses) , net of tax	152,258	(178,010)	(93,331)
Total other comprehensive income (loss) before reclassifications, net of tax	57,270	303,467	208,372
Amortization of unrealized holding losses on held-to-maturity securities	3,273	2,640	2,502
Gains (losses) realized in net income, net of tax	(6)	(1)	2
Accretion of net gain on terminated cash flow hedges, net of tax	(88)	(91)	(100)
Net yield adjustment from cash flow hedges currently in effect, net of tax	(186,656)	(201,732)	(9,590)
Amortization of prior service credit, net of tax	(3,090)	(3,124)	(3,076)
Amortization of actuarial losses, net of tax	64,751	42,489	15,291
Total other comprehensive income (loss)	(64,546)	143,648	213,401
Ending balance, net of tax	(127,578)	(63,032)	(206,680)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	195,386	50,701
Unrealized holding gains (losses), net, before tax	(95,114)	141,081
Total other comprehensive income (loss) before reclassifications, before tax	(95,114)	141,081
Amortization of unrealized holding losses on held-to-maturity securities	4,427	3,606
Gains (losses) realized in net income	(8)	(2)
Total other comprehensive income (loss), before tax	(90,695)	144,685
Ending balance, before tax	104,691	195,386	50,701
Total other comprehensive income (loss)	(66,977)	107,222	184,906
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	(650,087)	(464,548)	(354,502)
Current year benefit plans gains (loss), before tax	206,274	(238,218)	(126,618)
Total other comprehensive income (loss) before reclassifications, before tax	206,274	(238,218)	(126,618)
Amortization of prior service credit, before tax	(4,185)	(4,181)	(4,173)
Amortization of actuarial losses, before tax	87,722	56,860	20,745
Total other comprehensive income (loss), before tax	289,811	(185,539)	(110,046)
Ending balance, before tax	(360,276)	(650,087)	(464,548)
Total other comprehensive income (loss)	213,919	(138,645)	(81,116)
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	369,558	133,888	(14,719)
Foreign currency translation adjustment, before tax	(1,218)	2,724	1,381
Unrealized gain (losses) on cash flow hedges	(32,292)	505,042	160,373
Total other comprehensive income (loss) before reclassifications, before tax	(33,510)	507,766	161,754
Accretion of net gain (losses) on terminated cash flow hedges, before tax	(120)	(125)	(136)
Net yield adjustment from cash flow hedges currently in effect, before tax	(252,397)	(271,971)	(13,011)
Total other comprehensive income (loss), before tax	(286,027)	235,670	148,607
Ending balance, before tax	$ 83,531	369,558	133,888
Accumulated Net Unrealized Investment Gain Loss All Other
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax		$ 50,701	(200,107)
Unrealized holding gains (losses), net, before tax			247,411
Total other comprehensive income (loss) before reclassifications, before tax			247,411
Amortization of unrealized holding losses on held-to-maturity securities			3,394
Gains (losses) realized in net income			3
Total other comprehensive income (loss), before tax			250,808
Ending balance, before tax			$ 50,701