Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) $ in Millions	Jun. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Agency - Commercial
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	$ 7	$ 4
Unrealized Loss Position with Duration Under 12 Months	$ 1,478	$ 143
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	3,000,000	2
Unrealized Loss Position with Duration Under 12 Months | security	104,000,000	9
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(74)	0
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 81	$ 0
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0	0
Unrealized Loss Position with Duration Under 12 Months | security	24,000,000	1
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(3)	0
Agency - Residential
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 561	$ 291
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0	0
Unrealized Loss Position with Duration Under 12 Months | security	93,000,000	19
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(53)	(3)
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0
Unrealized Loss Position with Duration Under 12 Months	$ 85
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0
Unrealized Loss Position with Duration Under 12 Months | security	47,000,000
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0
Unrealized Loss Position with Duration Under 12 Months	(4)
Municipal obligations
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 13	$ 3
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0	0
Unrealized Loss Position with Duration Under 12 Months | security	7,000,000	1
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(1)	0
Corporate debt obligations
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0
Unrealized Loss Position with Duration Under 12 Months	$ 42
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0
Unrealized Loss Position with Duration Under 12 Months | security	11,000,000
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0
Unrealized Loss Position with Duration Under 12 Months	0
Other mortgage-backed securities
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 146	$ 147
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0	1
Unrealized Loss Position with Duration Under 12 Months | security	10,000,000	5
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	$ (26)	$ (1)