Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Cash Flows [Abstract]
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 91	$ 25
Cash flows from operating activities:
Net income attributable to common shareholders	(280)	(43)
Net income (loss)	(280)	(43)
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	0	0
Amortization of bond premium and discount	(4)	(12)
Share-based compensation	3	4
Deferred income taxes	(6)	(1)
Current income taxes	(5)	4
Unearned premiums, net	(7)	(36)
Losses and loss expenses, net	77	(119)
Ceded premiums payable	(1)	(1)
Premium receivables	13	8
Accrued interest payable	23	29
Amortization of insurance intangible assets	13	36
Net mark-to-market (gains) losses	2	0
Net realized investment gains	(8)	(17)
Variable interest entity activities	(3)	(16)
Increase (Decrease) in Derivative Assets and Liabilities	32	12
Other, net	63	57
Net cash used in operating activities	(87)	(95)
Cash flows from investing activities:
Proceeds from sales of bonds	221	641
Proceeds from matured bonds	49	35
Purchases of bonds	(150)	(183)
Proceeds from sales of other invested assets	243	2
Purchases of other invested assets	(195)	(29)
Change in short-term investments	67	(478)
Change in cash collateral receivable	(56)	57
Proceeds From Financial Guaranty Variable Interest Entity Assets	66	67
Other, net	(1)	0
Net cash provided by investing activities	244	112
Cash flows from financing activities:
Paydown of Ambac Note	(77)	(13)
Paydown of Financial Guaranty Variable Interest Entity Liabilities	(66)	(63)
AMPS Proceeds	0	3
Payment, Tax Withholding, Share-based Payment Arrangement	(3)	(2)
Net cash used in financing activities	(146)	(76)
Effect of Exchange Rate on Cash and Cash Equivalents	0	0
Net cash flow	10	(58)
Cash, cash equivalents, and restricted cash at end of period	$ 58	$ 22