Securitization Activities - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Assets securitized in a non-cash exchange for loans and investments	$ 274	$ 129	$ 413	$ 303
Net Asset related to Other Continuing Involvement	97		97		$ 52
Notional amount related to Other Continuing Involvement	1,990		1,990		1,430
Fair Value of Retained Interests	3,880		3,880		3,190
Other Retained Interests [Member]
Fair Value of Retained Interests	252		$ 252		$ 192
Weighted average life (years)			3 years 1 month 6 days		3 years 10 months 24 days
Maximum Exposure to Adverse Changes in the value of Other retained interests	$ 252		$ 252		$ 192