Fair Value Measurement - Fair Value of Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Carrying amount and estimated fair value financial instruments
Assets of consolidated investment vehicles (includes $353 and $331, at fair value)	$ 377	$ 366
Other assets (includes $123 and $123, at fair value)	713	706
Long-term debt	(1,695)	(1,694)
Other liabilities	(430)	(439)
Carrying Amount
Carrying amount and estimated fair value financial instruments
Assets of consolidated investment vehicles (includes $353 and $331, at fair value)	27	19
Other assets (includes $123 and $123, at fair value)	79	79
Financial guaranty insurance contracts	(2,153)	(2,244)
Long-term debt	(1,695)	(1,694)
Other liabilities	(24)	(15)
Estimated Fair Value
Carrying amount and estimated fair value financial instruments
Assets of consolidated investment vehicles (includes $353 and $331, at fair value)	27	19
Other assets (includes $123 and $123, at fair value)	80	80
Financial guaranty insurance contracts	(1,635)	(1,811)
Long-term debt	(1,597)	(1,593)
Other liabilities	$ (24)	$ (15)