Long-Term Debt (Details) - USD ($) $ in Thousands	3 Months Ended								4 Months Ended	8 Months Ended	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 01, 2013
Debt Instrument [Line Items]
Secured Debt	$ 130,571										$ 130,571
Junior surplus note of Ambac Assurance Segregated Account									$ 350,000					$ 350,000
Secured Debt [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount	$ 132,467										$ 132,467
5.1% Surplus Notes, General Account, Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	10.50%										10.50%
Debt Instrument, Repurchased Face Amount	$ 11,804										$ 11,804
Net realized gains (losses) on extinguishment of debt											1,246	$ 71,590
Debt Instrument, Face Amount	$ 881,496				$ 893,300						$ 881,496	893,300
5.1% Surplus Notes, Segregated Account, Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	10.50%										10.50%
Net realized gains (losses) on extinguishment of debt												3,134
Debt Instrument, Face Amount	$ 39,102				39,102						$ 39,102	39,102
5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	19.50%										19.50%
Debt Instrument, Face Amount	$ 378,039				378,039						$ 378,039	378,039
One State Street [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument Principal Amount Subject To Repurchase	13,056										13,056
Debt Instrument, Face Amount	$ 28,039										$ 28,039
Extinguishment of Debt, Amount													$ 8,043
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	8.40%										8.40%
Predecessor [Member]
Debt Instrument [Line Items]
Long-term debt									155,271
Net realized gains (losses) on extinguishment of debt									$ 0
Predecessor [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage									53.90%
Predecessor [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage									52.80%
Predecessor [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage									58.30%
Successor [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1,124,950				971,116				$ 940,313		$ 1,124,950	971,116
Net realized gains (losses) on extinguishment of debt	0	$ 1,420	$ (1,246)	$ (93)	(74,724)	$ 0	$ 0	$ 0		$ 0	81	(74,724)
Successor [Member] | Ambac Assurance Corporation [Member]
Debt Instrument [Line Items]
Long-term debt	1,124,950				971,116						1,124,950	971,116
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	715,211				696,330						715,211	696,330
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	31,725				30,479						31,725	30,479
Successor [Member] | Ambac Assurance Corporation [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member]
Debt Instrument [Line Items]
Long-term debt	247,443				$ 244,307						247,443	$ 244,307
Successor [Member] | Variable Interest Entities [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage					6.65%							6.65%
Long-term debt	$ 12,327,960				$ 12,882,076						$ 12,327,960	$ 12,882,076
Successor [Member] | 5.1% Surplus Notes, General Account, Due 2020 [Member] | Ambac Assurance Corporation [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.10%				5.10%						5.10%	5.10%
Debt Instruments Maturity Year											2020	2020
Successor [Member] | 5.1% Surplus Notes, Segregated Account, Due 2020 [Member] | Ambac Assurance Corporation [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.10%				5.10%						5.10%	5.10%
Debt Instruments Maturity Year											2020	2020
Successor [Member] | 5.1% Junior Surplus Notes, Segregated Account Due 2020 [Member] | Ambac Assurance Corporation [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	5.10%				5.10%						5.10%	5.10%
Debt Instruments Maturity Year											2020	2020
Consolidated Variable Interest Entities [Member]
Debt Instrument [Line Items]
Unpaid Principal Amount Of Fixed Rate Debt Accounted For Under Fair Value Option	$ 10,803,729				$ 11,925,499						$ 10,803,729	$ 11,925,499
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months	0										0
Long-term Debt, Maturities, Repayments of Principal in Year Two	0										0
Long-term Debt, Maturities, Repayments of Principal in Year Three	153,978										153,978
Long-term Debt, Maturities, Repayments of Principal in Year Four	363,498										363,498
Long-term Debt, Maturities, Repayments of Principal in Year Five	$ 60,665										$ 60,665
Consolidated Variable Interest Entities [Member] | Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	0.96%				0.69%						0.96%	0.69%
Consolidated Variable Interest Entities [Member] | Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	13.00%				13.00%						13.00%	13.00%
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Interest Rate on Securities Issued by Delaware Trust											2.80%