Quarterly Information (unaudited) Quarterly Information (unaudited) (Details) - Successor [Member] - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Gross Premiums Written	$ 2,129	$ (24,696)	$ (6,928)	$ (5,584)	$ (14,473)	$ (10,543)	$ (4,041)	$ (24,780)
Premiums Earned, Net, Financial Guarantee Insurance Contracts	31,523	52,989	43,152	47,613	49,867	53,218	41,402	52,800	$ 175,277	$ 197,287	$ 312,595
Net Investment Income	107,057	87,177	85,160	81,559	90,871	90,917	70,758	60,821	360,953	313,367	266,289
Other than Temporary Impairment Losses, Investments, Portion Recognized in Earnings, Net	(956)	(13,510)	(1,763)	(3,942)	(2,191)	(2,853)	(7,441)	(9,334)	20,171	21,819	25,659
Realized Investment Gains (Losses)	(68)	6,150	4,180	(4,896)	11,536	11,749	14,897	1,102	5,366	39,284	53,476
Gain (Loss) on Derivative Instruments, Net, Pretax	8,517	179	6,624	1,052	1,552	1,733	3,955	12,866	16,372	20,106	41,701
Gain (Loss) on Derivative Instruments Held for Trading Purposes, Net	23,027	3,984	34,068	(1,514)	83,992	(14,510)	(36,331)	(83,424)	59,565	(50,273)	(42,544)
Net realized gains (losses) on extinguishment of debt	0	0	2,179	2,741	0	24	3,586	1,235	4,920	4,845	81
Variable Interest Entity, Measure of Activity, Operating Income or Loss	21,237	(4,049)	(1,219)	3,701	2,026	2,057	8,987	(27,163)	19,670	(14,093)	31,569
Policyholder Benefits and Claims Incurred, Net, Financial Guarantee	102,269	209,806	66,100	135,011	215,492	(69,204)	(52,496)	(105,281)	513,186	(11,489)	(768,707)
Amortization of insurance intangible assets	34,168	45,690	33,471	37,525	40,152	44,553	39,013	50,890	150,854	174,608	169,557
Other Underwriting Expense	28,694	33,791	31,051	27,980	36,190	21,466	27,995	28,009	121,516	113,660	102,702
Interest Expense, Debt	30,990	29,145	28,234	31,572	31,712	31,493	30,709	30,430	119,941	124,344	116,537
Goodwill, Impairment Loss									0	0	514,511
Pre-tax (loss) income from continuing operations	(6,917)	(185,466)	13,992	(105,860)	(86,059)	116,720	61,511	12,854	(284,251)	105,026	510,058
Net Income (Loss) Attributable to Parent	$ (19,479)	$ (190,905)	$ 7,110	$ (125,441)	$ (94,693)	$ 101,474	$ 58,647	$ 9,415	$ (328,715)	$ 74,843	$ 493,403
Earnings Per Share, Basic	$ (0.43)	$ (4.20)	$ 0.16	$ (2.77)	$ (2.09)	$ 2.24	$ 1.30	$ 0.21	$ (7.25)	$ 1.66	$ 10.92
Earnings Per Share, Diluted	$ (0.43)	$ (4.20)	$ 0.16	$ (2.77)	$ (2.09)	$ 2.22	$ 1.29	$ 0.21	$ (7.25)	$ 1.64	$ 10.72