Segment Information - Summary of Financial Information by Reportable Segment (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Revenues:
Total revenues before expenses and reorganization items	$ 230,752	$ 57,333	$ 386,243	$ 166,471
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	286,095	(210,412)	502,675	(51,114)
Total assets	25,513,636	27,723,353	25,513,636	27,723,353	$ 25,159,864
Net investment income	64,753	80,093	137,736	150,894
Amortization of insurance intangible assets	38,088	36,256	75,520	67,970
Interest expense	28,173	31,953	56,081	64,281
Reorganization items	0	186	0	209
Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	229,697	57,333	384,160	166,471
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	285,040	(210,412)	500,592	(51,114)
Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	1,055	0	2,083	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	1,055	0	2,083	0
Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items	177,507		369,578	267,956
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	235,895	(170,082)	491,361	37,022
Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items	51,008		13,070	(101,531)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	50,122	(48,869)	11,230	(103,852)
Corporate, Non-Segment [Member]
Revenues:
Total revenues before expenses and reorganization items	2,274	8,877	3,632	17,535
Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items	(37)	(8,554)	(37)	(17,489)
Operating Segments [Member] | Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items	5	105,028
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations		(9,397)
Total assets	24,915,205	27,326,877	24,915,205	27,326,877
Net investment income	62,508	79,633	133,978	150,017
Amortization of insurance intangible assets	38,088	36,256	75,520	67,970
Interest expense	27,842	31,514	55,427	63,395
Operating Segments [Member] | Financial Guarantee [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	177,502	104,703	369,316	267,256
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	236,680	(160,685)	492,685	55,576
Operating Segments [Member] | Financial Guarantee [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0	0	0
Operating Segments [Member] | Financial Guarantee [Member] | Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items		325
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(785)
Operating Segments [Member] | Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items	(131)	(48,018)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations		(415)
Total assets	339,902	365,678	339,902	365,678
Net investment income	134	419	262	813
Amortization of insurance intangible assets	0	0	0	0
Interest expense	331	439	654	886
Operating Segments [Member] | Financial Services [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	51,139	(47,411)	13,431	(100,849)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	50,374	(48,454)	11,794	(102,983)
Operating Segments [Member] | Financial Services [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0	0	0
Operating Segments [Member] | Financial Services [Member] | Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items		(607)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(252)
Corporate, Non-Segment [Member]
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(85)	8,539	(79)	15,716
Total assets	276,098	247,135	276,098	247,135
Net investment income	2,111	41	3,496	64
Amortization of insurance intangible assets	0	0	0	0
Corporate, Non-Segment [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	1,056	41	1,413	64
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(2,014)	(1,273)	(3,887)	(3,707)
Corporate, Non-Segment [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	1,055	0	2,083	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	1,055	0	2,083	0
Corporate, Non-Segment [Member] | Corporate, Non-Segment [Member]
Pre-tax income (loss) from continuing operations:
Interest expense	0	0	0	0
Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items	(37)	(8,554)	(37)	(17,489)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	163	0	163	0
Total assets	(17,569)	(216,337)	(17,569)	(216,337)
Net investment income	0	0	0	0
Amortization of insurance intangible assets	0	0	0	0
Interest expense	0	0	0	0
Inter-segment Eliminations [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0	0	0
Inter-segment Eliminations [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0	0	0
Inter-segment Eliminations [Member] | Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items			262	700
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			(1,324)	(18,554)
Inter-segment Eliminations [Member] | Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items			(361)	(682)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			(564)	(869)
Inter-segment Eliminations [Member] | Corporate, Non-Segment [Member]
Revenues:
Total revenues before expenses and reorganization items	163	8,836	136	17,471
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	$ 874	$ 9,812	$ 1,725	$ 19,423