Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 25,794,531	$ 16,720,304	$ 17,903,405	$ 16,187,283
Net gain (loss) during period	(393,503)	(33,445)	(772,415)	(147,387)
Ending balance	25,256,493	17,528,771	25,256,493	17,528,771
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			77,625
Net gain (loss) during period			(425,770)
Ending balance	(348,145)		(348,145)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(267,145)
Net gain (loss) during period			9,160
Ending balance	(257,985)		(257,985)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			61,942
Net gain (loss) during period			(355,805)
Ending balance	(293,863)		(293,863)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(506,490)	(176,974)	(127,578)	(63,032)
Net gain (loss) during period			(772,415)
Ending balance	$ (899,993)	$ (210,419)	$ (899,993)	$ (210,419)