Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 25,377,171	$ 17,876,020	$ 25,317,990	$ 17,903,405
Net gain (loss) during period	(219,795)	(129,105)	(74,770)	(378,912)
Ending balance	25,800,933	25,794,531	25,800,933	25,794,531
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(329,168)
Net gain (loss) during period			1,330
Ending balance	(327,838)		(327,838)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(202,186)
Net gain (loss) during period			(3,253)
Ending balance	(205,439)		(205,439)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(258,676)
Net gain (loss) during period			(72,847)
Ending balance	(331,523)		(331,523)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(645,005)	(377,385)	(790,030)	(127,578)
Net gain (loss) during period			(74,770)
Ending balance	$ (864,800)	$ (506,490)	$ (864,800)	$ (506,490)