Segment Information - Summary of Financial Information by Reportable Segment (Detail) (Successor [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Revenues:
Total revenues before expenses and reorganization items	$ 155,491	$ 109,138
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	216,580	159,298
Total assets	25,386,610	27,114,248	25,159,864
Net investment income	72,983	70,801
Amortization of insurance intangible assets	37,432	31,714
Interest expense	27,908	32,328
Reorganization items	0	23
Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	154,463	109,138
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	215,552	159,298
Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	1,028	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	1,028	0
Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items	192,071	162,928
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	255,466	208,001
Total assets	24,672,977	26,535,119
Net investment income	71,470	70,384
Amortization of insurance intangible assets	37,432	31,714
Interest expense	27,585	31,881
Financial Guarantee [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	191,814	162,553
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	256,005	217,158
Financial Guarantee [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Financial Guarantee [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items	257	375
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(539)	(9,157)
Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items	(37,938)	(53,513)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(38,892)	(54,904)
Total assets	431,445	534,256
Net investment income	128	394
Amortization of insurance intangible assets	0	0
Interest expense	323	447
Financial Services [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	(37,708)	(53,438)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(38,580)	(54,450)
Financial Services [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Financial Services [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items	(230)	(75)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(312)	(454)
Corporate and Other [Member]
Revenues:
Total revenues before expenses and reorganization items	1,358	8,658
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	6	6,201
Total assets	282,188	44,873
Net investment income	1,385	23
Amortization of insurance intangible assets	0	0
Interest expense	0	0
Corporate and Other [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	357	23
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	(1,873)	(3,410)
Corporate and Other [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	1,028	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	1,028	0
Corporate and Other [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items	(27)	8,635
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	851	9,611
Inter-segment Eliminations [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items	0	(8,935)
Inter-segment Eliminations [Member] | Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items	0	(8,935)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Total assets	0	0
Net investment income	0	0
Amortization of insurance intangible assets	0	0
Interest expense	0	0
Inter-segment Eliminations [Member] | Inter-segment Eliminations [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Inter-segment Eliminations [Member] | Inter-segment Eliminations [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items	0	0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	0	0
Inter-segment Eliminations [Member] | Inter-segment Eliminations [Member] | Intersegment [Member]
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	$ 0	$ 0