Accounting Policies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023	Dec. 31, 2022
Significant Accounting Policies [Line Items]
Total assets	$ 30,825		$ 30,825			$ 28,831
Total liabilities	26,844		26,844			24,779
Operating lease liability	$ 189		$ 189			$ 116
Operating lease liability, current, Statement of Financial Position	Other Liabilities		Other Liabilities			Other Liabilities
Operating lease right-of-use asset	$ 167		$ 167			$ 103
Operating lease, right-of-use asset, Statement of Financial Position	Other Assets		Other Assets			Other Assets
Operating lease, renewal term					10 years
Weighted average common shares adjustment related to stock-based compensation (shares)	100,000	200,000	100,000	200,000
Anti-dilutive potential common shares related to stock-based compensation plans (shares)	0	0	0	0
Maturities of short term investments			3 months
New collateralized loan obligation temporary warehousing entities
Significant Accounting Policies [Line Items]
Total assets	$ 120		$ 120
Total liabilities	$ 97		$ 97