Segment Information - Summary of Financial Information by Reportable Segment (Detail) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended	4 Months Ended	12 Months Ended	2 Months Ended	3 Months Ended						8 Months Ended	12 Months Ended
	Apr. 30, 2013	Mar. 31, 2013	Apr. 30, 2013	Dec. 31, 2012	Jun. 30, 2013	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Dec. 31, 2013	Dec. 31, 2014
Pre-tax income (loss) from continuing operations:
Total assets	$ 28,853,435		$ 28,853,435
Predecessor [Member]
Revenues:
Total revenues before expenses and reorganization items			640,388	685,689
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations	3,065,124	282,909	3,348,033	(256,505)
Total assets	28,853,435		28,853,435	27,085,265
Net investment income	32,226	84,514	116,740	382,902
Amortization of insurance intangible assets	0	0	0	0
Interest expense	7,860	23,165	31,025	112,320
Reorganization items	(2,747,239)	2,059	(2,745,180)	7,215
Predecessor [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items			640,388	685,689
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			3,348,033	(256,505)
Predecessor [Member] | 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
Predecessor [Member] | Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items			633,950	763,520
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			1,831,105	(162,217)
Total assets	28,287,321		28,287,321	26,519,480
Net investment income			115,129	365,912
Interest expense			29,718	105,973
Reorganization items			(1,231,550)	0
Predecessor [Member] | Financial Guarantee [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items			633,010	758,331
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			1,831,237	(162,797)
Predecessor [Member] | Financial Guarantee [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items			940	5,189
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			(132)	580
Predecessor [Member] | Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items			6,457	(77,969)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			2,293	(88,204)
Total assets	536,711		536,711	533,528
Net investment income			1,572	16,769
Interest expense			1,307	6,347
Reorganization items			1,505	0
Predecessor [Member] | Financial Services [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items			7,339	(72,977)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			3,394	(82,429)
Predecessor [Member] | Financial Services [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items			(882)	(4,992)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			(1,101)	(5,775)
Predecessor [Member] | Corporate and Other [Member]
Revenues:
Total revenues before expenses and reorganization items			39	980
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			1,514,635	(6,084)
Total assets	29,403		29,403	32,257
Net investment income			39	221
Interest expense			0	0
Reorganization items			(1,515,135)	7,215
Predecessor [Member] | Corporate and Other [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items			39	335
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			1,513,402	(11,279)
Predecessor [Member] | Corporate and Other [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items			0	645
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			1,233	5,195
Successor [Member]
Revenues:
Total revenues before expenses and reorganization items												581,048	328,670
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations					205,795	459,594	84,773	(210,412)	159,298	74,920	231,601	512,316	493,253
Total assets	28,853,435		28,853,435			25,159,864				27,092,477		27,092,477	25,159,864
Net investment income					26,196	66,471	83,581	80,093	70,801	68,124	52,126	146,446	300,946
Amortization of insurance intangible assets					24,952	41,952	41,908	36,256	31,714	37,233	37,473	99,658	151,830
Interest expense					21,144	31,354	31,841	31,953	32,328	31,989	31,817	84,950	127,476
Reorganization items					424	0	2	186	23	65	4	493	211
Successor [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items												581,048	327,275
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												512,316	491,858
Successor [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items													1,395
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													1,395
Successor [Member] | 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
Successor [Member] | Financial Guarantee [Member]
Revenues:
Total revenues before expenses and reorganization items												466,538	507,801
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												184,786	659,307
Total assets						24,444,514				26,582,635		26,582,635	24,444,514
Net investment income												145,269	298,020
Amortization of insurance intangible assets												99,658	151,830
Interest expense												83,595	125,892
Reorganization items												0	0
Successor [Member] | Financial Guarantee [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items												464,701	506,558
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												405,004	684,750
Successor [Member] | Financial Guarantee [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items													0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													0
Successor [Member] | Financial Guarantee [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items												1,837	1,243
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												(220,218)	(25,443)
Successor [Member] | Financial Services [Member]
Revenues:
Total revenues before expenses and reorganization items												114,967	(180,888)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												111,703	(184,486)
Total assets						436,072				472,886		472,886	436,072
Net investment income												1,115	1,123
Amortization of insurance intangible assets												0	0
Interest expense												1,355	1,584
Reorganization items												0	0
Successor [Member] | Financial Services [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items												116,177	(179,691)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												113,347	(182,941)
Successor [Member] | Financial Services [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items													0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													0
Successor [Member] | Financial Services [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items												(1,210)	(1,197)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												(1,644)	(1,545)
Successor [Member] | Corporate and Other [Member]
Revenues:
Total revenues before expenses and reorganization items												219,351	25,102
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												215,827	18,432
Total assets						279,278				36,956		36,956	279,278
Net investment income												62	1,803
Amortization of insurance intangible assets												0	0
Interest expense												0	0
Reorganization items												493	211
Successor [Member] | Corporate and Other [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items												170	408
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												(6,035)	(9,951)
Successor [Member] | Corporate and Other [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items													1,395
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													1,395
Successor [Member] | Corporate and Other [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items												219,181	23,299
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												221,862	26,988
Inter-segment Eliminations [Member] | Predecessor [Member]
Revenues:
Total revenues before expenses and reorganization items			(58)	(842)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			0	0
Net investment income			0	0
Interest expense			0	0
Reorganization items			0	0
Inter-segment Eliminations [Member] | Predecessor [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] | Predecessor [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items			(58)	(842)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations			0	0
Inter-segment Eliminations [Member] | Successor [Member]
Revenues:
Total revenues before expenses and reorganization items												(219,808)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												0
Total assets										0		0
Net investment income												0
Amortization of insurance intangible assets												0
Interest expense												0
Reorganization items												0
Inter-segment Eliminations [Member] | Successor [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items												0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												0
Inter-segment Eliminations [Member] | Successor [Member] | Intersegment [Member]
Revenues:
Total revenues before expenses and reorganization items												(219,808)	(23,345)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations												0
Inter-segment Eliminations [Member] | Successor [Member] | Inter-segment Eliminations [Member]
Revenues:
Total revenues before expenses and reorganization items													(23,345)
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													0
Total assets						0							0
Net investment income													0
Amortization of insurance intangible assets													0
Interest expense													0
Reorganization items													0
Inter-segment Eliminations [Member] | Successor [Member] | Inter-segment Eliminations [Member] | Unaffiliated Customers [Member]
Revenues:
Total revenues before expenses and reorganization items													0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													0
Inter-segment Eliminations [Member] | Successor [Member] | Inter-segment Eliminations [Member] | Equity Method Investee [Member]
Revenues:
Total revenues before expenses and reorganization items													0
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													0
Inter-segment Eliminations [Member] | Successor [Member] | Inter-segment Eliminations [Member] | Intersegment [Member]
Pre-tax income (loss) from continuing operations:
Pre-tax (loss) income from continuing operations													$ 0