Business Combinations - Pro Forma Information (Details) - USD ($)	1 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 05, 2019	Dec. 31, 2018
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net income	$ 251,000,000	$ 5,972,000,000	$ 6,249,000,000
Net interest income	515,000,000
Net interest income		14,018,000,000	13,844,000,000
Noninterest income	$ 217,000,000
Noninterest income		$ 8,528,000,000	$ 8,114,000,000