Quarterly Information (unaudited) Quarterly Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gross Premiums Written	$ 1,000	$ 13,000	$ 1,000	$ 11,000	$ (2,000)	$ 13,000	$ 21,000	$ 3,000
Premiums Earned, Net, Financial Guarantee Insurance Contracts	18,000	15,000	11,000	10,000	20,000	10,000	8,000	28,000	$ 54,000	$ 66,000	$ 111,000
Net Investment Income	53,000	37,000	52,000	(21,000)	42,000	45,000	86,000	55,000	122,000	227,000	273,000
Realized Investment Gains (Losses)	2,000	2,000	10,000	8,000	9,000	18,000	36,000	17,000	22,000	81,000	108,000
Derivative, Gain (Loss) on Derivative, Net	12,000	7,000	2,000	(70,000)	12,000	(10,000)	(35,000)	(16,000)	(50,000)	(50,000)	7,000
Net realized gains (losses) on extinguishment of debt									0	0	3,000
Other income	1,000	2,000	0	0	1,000	141,000	(9,000)	1,000	3,000	134,000	5,000
Variable Interest Entity, Measure of Activity, Operating Income or Loss	3,000	0	0	3,000	7,000	11,000	3,000	16,000	5,000	38,000	3,000
Policyholder Benefits and Claims Incurred, Net, Financial Guarantee	(9,000)	(83,000)	(16,000)	(117,000)	(97,000)	(37,000)	133,000	12,000	(225,000)	(13,000)	224,000
Amortization of insurance intangible assets	16,000	14,000	14,000	13,000	15,000	17,000	226,000	36,000	57,000	295,000	107,000
Other Underwriting Expense	26,000	23,000	21,000	24,000	23,000	26,000	29,000	25,000	92,000	103,000	112,000
Interest Expense, Debt	50,000	50,000	58,000	63,000	66,000	67,000	67,000	68,000	222,000	269,000	242,000
Pre-tax (loss) income from continuing operations	(12,000)	(108,000)	(33,000)	(287,000)	(111,000)	69,000	(100,000)	(41,000)	(440,000)	(183,000)	273,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest									(437,000)	(216,000)	267,000
Net Income (Loss) Attributable to Parent	$ (14,000)	$ (108,000)	$ (35,000)	$ (280,000)	$ (110,000)	$ 66,000	$ (128,000)	$ (43,000)	$ (437,000)	$ (216,000)	$ 186,000
Earnings Per Share, Basic	$ (0.31)	$ (2.33)	$ (0.77)	$ (6.07)	$ (2.40)	$ 1.44	$ (2.79)	$ (0.94)	$ (9.47)	$ (4.69)	$ 4.07
Earnings Per Share, Diluted	$ (0.31)	$ (2.33)	$ (0.77)	$ (6.07)	$ (2.40)	$ 1.41	$ (2.79)	$ (0.94)	$ (9.47)	$ (4.69)	$ 3.99