Consolidated Statements of Cash Flows - Successor [Member] - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	$ 45,450	$ 59,253
Cash flows from operating activities:
Net income attributable to common shareholders	310,017	(118,331)
Net income (loss)	310,017	(118,331)
Adjustments to reconcile net income to net cash used in operating activities:
Depreciation and amortization	363	533
Amortization of bond premium and discount	(102,602)	(83,180)
Share-based compensation	8,765	2,385
Deferred income taxes	(880)	146
Current income taxes	(23,564)	12,283
Unearned premiums, net	(57,310)	(63,820)
Losses and loss expenses, net	(1,435,042)	206,693
Ceded premiums payable	(2,282)	(2,865)
Investment income due and accrued	4,433	1,755
Premium receivables	32,432	8,378
Accrued interest payable	(89,633)	6,576
Amortization of insurance intangible assets	51,878	70,996
Net mark-to-market (gains) losses	760	(6,343)
Net realized investment gains	(52,010)	716
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, Net of Tax, Portion Attributable to Parent, Available-for-sale Securities	1,313	5,705
Other-than-temporary impairment charges	1,313	5,705
(Gain) loss on extinguishment of debt	(3,121)	(4,920)
Variable interest entity activities	(1,151)	(2,482)
Increase (Decrease) in Derivative Assets and Liabilities	(120)	(211,149)
Other, net	46,166	11,455
Net cash used in operating activities	(1,311,588)	(165,469)
Cash flows from investing activities:
Proceeds from sales of bonds	623,495	885,507
Proceeds from matured bonds	214,066	390,309
Purchases of bonds	(163,917)	(986,364)
Proceeds from sales of other invested assets	51,402	177,805
Purchases of other invested assets	(18,862)	(161,375)
Change in short-term investments	164,860	(73,092)
Loans, net		(5,965)
Change in cash collateral receivable	781	73,174
Proceeds From Financial Guaranty Variable Interest Entity Assets	137,983	120,142
Other, net	5,543	(4,534)
Net cash provided by investing activities	1,015,351	415,607
Cash flows from financing activities:
Proceeds From Issuance of Tier II Notes	240,000	0
Proceeds from Sale of Senior Surplus Notes	4,571	0
Paydown of Ambac Note	(113,457)	0
Paydowns of a secured borrowing	(73,993)	(16,929)
Proceeds from warrant exercises	3
Payments for Repurchase of Warrants	8,092
Paydown of Financial Guaranty Variable Interest Entity Liabilities	(137,984)	(115,534)
Payments for investment agreement draws	0	(82,358)
Payments for extinguishment of long-term debt	(191,258)	(69,499)
Payments of Debt Issuance Costs	(9,221)	0
Payments Related to Tax Withholding for Share-based Compensation	(1,116)	(1,268)
Net cash used in financing activities	(282,455)	(285,588)
Effect of Exchange Rate on Cash and Cash Equivalents	(539)	(1,195)
Net cash flow	(579,231)	(36,645)
Cash, cash equivalents, and restricted cash at end of period	$ 44,398	$ 54,238