Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Loss on securitization of assets			$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts	$ 23,000,000		23,000,000		$ 23,000,000
Total assets of partnerships in which the company invested	204,032,889,000		204,032,889,000		155,107,160,000
Investment in partnership carrying amount	1,400,000,000		1,400,000,000		933,000,000
Unfunded commitments includes carrrying amount of its investments	538,000,000		538,000,000		361,000,000
Maximum exposure to loss of investments in real estate partnerships	1,700,000,000		1,700,000,000
Investments amortized to income tax expense	36,000,000	$ 19,000,000	57,000,000	$ 38,000,000
Federal tax credits and other federal tax benefits recognized	42,000,000	$ 22,000,000	65,000,000	$ 43,000,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested	$ 8,400,000,000		$ 8,400,000,000		$ 3,000,000,000.0