Comprehensive Income - Accumulated Other Comprehensive Income (Loss), Net (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 25,317,990	$ 17,903,405
Net gain (loss) during period	145,025	(249,807)
Ending balance	25,377,171	17,876,020
Investment Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(329,168)
Net gain (loss) during period	65,140
Ending balance	(264,028)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(202,186)
Net gain (loss) during period	(2,242)
Ending balance	(204,428)
Accumulated Other Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(258,676)
Net gain (loss) during period	82,127
Ending balance	(176,549)
Accumulated Other Comprehensive Income (Loss), Net [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(790,030)	(127,578)
Net gain (loss) during period	145,025
Ending balance	$ (645,005)	$ (377,385)