Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 25,800,933	$ 25,794,531	$ 25,317,990	$ 17,903,405
Net loss during period	(77,078)	(393,503)	(151,848)	(772,415)
Ending balance	26,196,502	25,256,493	26,196,502	25,256,493
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(329,168)
Net loss during period			(1,778)
Ending balance	(330,946)		(330,946)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(202,186)
Net loss during period			(4,511)
Ending balance	(206,697)		(206,697)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(258,676)
Net loss during period			(145,559)
Ending balance	(404,235)		(404,235)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(864,800)	(506,490)	(790,030)	(127,578)
Net loss during period			(151,848)
Ending balance	$ (941,878)	$ (899,993)	$ (941,878)	$ (899,993)