Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 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
Total assets of partnerships in which the company invested	149,863,552,000		155,107,160,000
Investment in partnership carrying amount	906,000,000		933,000,000
Unfunded commitments includes carrrying amount of its investments	343,000,000		361,000,000
Maximum exposure to loss of investments in real estate partnerships	1,200,000,000
Investments amortized to income tax expense	20,000,000	$ 19,000,000
Federal tax credits and other federal tax benefits recognized	23,000,000	$ 21,000,000
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested	$ 3,200,000,000		$ 3,000,000,000.0