Variable Interest Entities and Asset Securitizations - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Loss on securitization of assets				$ 0
Other assets for its "investment" in the common securities recognized by the company of various trusts		$ 22,000,000		22,000,000		$ 22,000,000
Total assets of partnerships in which the company invested		209,124,316,000		209,124,316,000		200,729,841,000
Investment in partnership carrying amount		1,400,000,000		1,400,000,000		1,500,000,000
Unfunded commitments includes carrrying amount of its investments		491,000,000		491,000,000		545,000,000
Contingent Commitments to Provide Additional Capital Contributions to Partnerships		49,000,000		49,000,000
Maximum exposure to loss of investments in real estate partnerships		2,100,000,000		2,100,000,000
Investments amortized to income tax expense		46,000,000	$ 37,000,000	128,000,000	$ 94,000,000
Federal tax credits and other federal tax benefits recognized		52,000,000	$ 44,000,000	147,000,000	$ 108,000,000
Remaining balance of loans and leases		133,133,497,000		133,133,497,000		132,074,156,000
Loans and leases		130,302,558,000		130,302,558,000		129,638,832,000
Asset-backed notes		516,668,000		516,668,000
Senior notes		3,741,161,000		3,741,161,000		1,249,141,000
Asset-backed Notes [Member]
Remaining balance of loans and leases		643,000,000		643,000,000
Loans and leases	$ 666,000,000
Asset-backed notes	$ 88,000,000	517,000,000		517,000,000
Loans and leases average rate	5.84%
Senior notes	$ 550,000,000
Asset-backed notes weighed average estimated life	2 years
Variable Interest Entity Primary Beneficiary [Member]
Total assets of partnerships in which the company invested		$ 9,800,000,000		$ 9,800,000,000		$ 9,200,000,000