Other Securities - Additional Information (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Banking and Thrift [Abstract]
Federal Home Loan Bank stock	$ 256,000,000	$ 209,000,000
Federal Reserve Bank stock	123,000,000	122,000,000
Other non-marketable equity securities	1,000,000	1,000,000
Total non-marketable equity securities	380,000,000	332,000,000
Other non-marketable equity securities, impairment	$ 0	$ 0