Investment Securities - Summary of Unrealized Loss Positions on Investment Securities (Details) $ in Millions	Sep. 30, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Agency - Commercial
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	$ 4	$ 4
Unrealized Loss Position with Duration Under 12 Months	$ 1,836	$ 143
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	2,000,000	2
Unrealized Loss Position with Duration Under 12 Months | security	114,000,000	9
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(150)	0
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 69	$ 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	(6)	0
Agency - Residential
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	202	0
Unrealized Loss Position with Duration Under 12 Months	$ 306	$ 291
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	13,000,000	0
Unrealized Loss Position with Duration Under 12 Months | security	80,000,000	19
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ (49)	$ 0
Unrealized Loss Position with Duration Under 12 Months	(33)	(3)
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0
Unrealized Loss Position with Duration Under 12 Months	$ 76
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	(8)
Municipal obligations
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0	0
Unrealized Loss Position with Duration Under 12 Months	$ 14	$ 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	10,000,000	1
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0	$ 0
Unrealized Loss Position with Duration Under 12 Months	(2)	0
Corporate debt obligations
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	0
Unrealized Loss Position with Duration Under 12 Months	$ 52
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	0
Unrealized Loss Position with Duration Under 12 Months | security	13,000,000
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ 0
Unrealized Loss Position with Duration Under 12 Months	(1)
Other mortgage-backed securities
Fair Value
Unrealized Loss Position with Duration 12 Months and Over	56	0
Unrealized Loss Position with Duration Under 12 Months	$ 79	$ 147
Number of Securities
Unrealized Loss Position with Duration 12 Months and Over | security	3,000,000	1
Unrealized Loss Position with Duration Under 12 Months | security	7,000,000	5
Unrealized Loss
Unrealized Loss Position with Duration 12 Months and Over	$ (12)	$ 0
Unrealized Loss Position with Duration Under 12 Months	$ (26)	$ (1)