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
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	$ (172,054)	$ (85,143)
Unrealized holding losses, net, before tax	(184,955)	(32,025)
Foreign currency translation adjustment, before tax	(2,123)	684
Unrealized losses on cash flow hedges	(115,724)	(9,498)
Total other comprehensive income (loss) before reclassifications, before tax	(302,802)	(40,839)
Amortization of unrealized holding losses on held-to-maturity securities	1,119	990
Gains realized in net income		(3)
Accretion of net gain on terminated cash flow hedges, before tax	(30)	(30)
Net yield adjustment from cash flow hedges currently in effect, before tax	(38,019)	(82,044)
Amortization of prior service credit, before tax	(950)	(1,050)
Amortization of actuarial losses, before tax	4,300	21,850
Total other comprehensive income (loss), before tax	(336,382)	(101,126)
Ending balance, before tax	(508,436)	(186,269)
Beginning balance, tax	44,476	22,111
Unrealized holding losses, net, tax	47,758	8,907
Foreign currency translation adjustment, tax	475	(136)
Unrealized losses on cash flow hedges	29,885	2,571
Total other comprehensive income (loss) before reclassifications, tax	78,118	11,342
Amortization of unrealized holding losses on held-to-maturity securities, tax	(289)	(276)
Gains realized in net income, tax		1
Accretion of net gain on terminated cash flow hedges, tax	9	9
Net yield adjustment from cash flow hedges currently in effect, tax	9,818	22,215
Amortization of prior service credit, tax	305	384
Amortization of actuarial losses, tax	(1,386)	(7,995)
Total other comprehensive income (loss), tax	86,575	25,680
Ending balance, tax	131,051	47,791
Beginning balance, net of tax	(127,578)	(63,032)
Unrealized holding losses, net of tax	(137,197)	(23,118)
Foreign currency translation adjustments	(1,648)	548
Unrealized losses on cash flow hedges, net of tax	(85,839)	(6,927)
Total other comprehensive income (loss) before reclassifications, net of tax	(224,684)	(29,497)
Amortization of unrealized holding losses on held-to-maturity securities	830	714
Gains realized in net income, net of tax		(2)
Accretion of net gain on terminated cash flow hedges, net of tax	(21)	(21)
Net yield adjustment from cash flow hedges currently in effect, net of tax	(28,201)	(59,829)
Amortization of prior service credit, net of tax	(645)	(666)
Amortization of actuarial losses, net of tax	2,914	13,855
Total other comprehensive income (loss)	(249,807)	(75,446)
Ending balance, net of tax	(377,385)	(138,478)
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	104,691	195,386
Unrealized holding losses, net, before tax	(184,955)	(32,025)
Total other comprehensive income (loss) before reclassifications, before tax	(184,955)	(32,025)
Amortization of unrealized holding losses on held-to-maturity securities	1,119	990
Gains realized in net income		(3)
Total other comprehensive income (loss), before tax	(183,836)	(31,038)
Ending balance, before tax	(79,145)	164,348
Total other comprehensive income (loss)	(136,367)
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	(950)	(1,050)
Amortization of actuarial losses, before tax	4,300	21,850
Total other comprehensive income (loss), before tax	3,350	20,800
Ending balance, before tax	(356,926)	(629,287)
Total other comprehensive income (loss)	2,269
Other [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance, before tax	83,531	369,558
Foreign currency translation adjustment, before tax	(2,123)	684
Unrealized losses on cash flow hedges	(115,724)	(9,498)
Total other comprehensive income (loss) before reclassifications, before tax	(117,847)	(8,814)
Accretion of net gain on terminated cash flow hedges, before tax	(30)	(30)
Net yield adjustment from cash flow hedges currently in effect, before tax	(38,019)	(82,044)
Total other comprehensive income (loss), before tax	(155,896)	(90,888)
Ending balance, before tax	$ (72,365)	$ 278,670