Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Statement of Cash Flows [Abstract]
Net cash flows provided by (used in) operating activities	$ (365)	$ 352
Fixed-maturity securities:
Purchases	(688)	(1,478)
Sales	1,306	908
Maturities and paydowns	664	746
Short-term investments with original maturities of over three months:
Purchases	(216)	(148)
Sales	2	1
Maturities and paydowns	206	136
Net sales (purchases) of short-term investments with original maturities of less than three months	(404)	(80)
Net proceeds from paydowns on financial guaranty variable interest entities’ assets	119	90
Net proceeds from sales of financial guaranty variable interest entities’ assets	51	0
Other	30	19
Net cash flows provided by (used in) investing activities	1,070	194
Financing activities
Dividends paid	(56)	(55)
Repurchases of common stock	(340)	(380)
Net paydowns of financial guaranty variable interest entities’ liabilities	(162)	(90)
Paydown of long-term debt	(4)	(73)
Other	(16)	(8)
Net cash flows provided by (used in) financing activities	(578)	(606)
Effect of foreign exchange rate changes	(2)	(2)
Increase (decrease) in cash and restricted cash	125	(62)
Cash and restricted cash at beginning of period (see Note 7)	104	144
Cash and restricted cash at end of period (see Note 7)	229	82
Supplemental cash flow information
Income taxes	(2)	(5)
Interest on long-term debt	$ 51	$ 66