Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Statement of Cash Flows [Abstract]
Net cash flows provided by (used in) operating activities			$ (445)	$ (198)
Fixed-maturity securities:
Purchases			(627)	(503)
Sales	$ 404	$ 443	490	914
Maturities and paydowns			373	506
Short-term investments with maturities of over three months:
Purchases			(103)	(209)
Sales			4	2
Maturities and paydowns			60	174
Net sales (purchases) of short-term investments with original maturities of less than three months			487	(389)
Net proceeds from paydowns on financial guaranty variable interest entities’ assets			55	50
Net proceeds from sales of financial guaranty variable interest entities' assets			0	51
Proceeds from sales and return of capital of other invested assets			5	35
Other			(11)	0
Net cash flows provided by (used in) investing activities			733	631
Financing activities
Dividends paid			(37)	(39)
Repurchases of common stock			(280)	(190)
Net paydowns of financial guaranty variable interest entities’ liabilities			(52)	(95)
Paydown of long-term debt			(22)	(4)
Other			(12)	(15)
Proceeds from issuance of collateralized loan obligations			362	0
Contributions from noncontrolling interests to investment vehicles			66	0
Distributions to noncontrolling interests from investment vehicles			(16)	0
Net cash flows provided by (used in) financing activities			9	(343)
Effect of foreign exchange rate changes			(7)	0
Increase (decrease) in cash and restricted cash			290	90
Cash and restricted cash at beginning of period			183	104	$ 104
Supplemental cash flow information
Income taxes paid			0
Income tax refunds				(3)
Cash and restricted cash at end of period	473	194	473	194	183
Interest on long-term debt			41	42
Purchases of fixed-maturity investments			0	(139)
Cash	293	190	293	190	$ 169
Restricted cash (included in other assets)	5	4	5	4
Cash of consolidated investment vehicles (see Note 11)	$ 175	$ 0	$ 175	$ 0