Financial Guarantee Insurance Contracts - Summary of Information Related to Policies Currently Included in Ambac's Loss Reserves or Subrogation Recoverable (Detail) (Successor Ambac [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014 Policies	Dec. 31, 2013 Policies
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	364	339
Remaining weighted-average contract period (in years)	14 years	14 years
Gross insured contractual payments outstanding:
Principal	$ 22,010,268	$ 22,206,789
Interest	8,294,958	8,397,133
Total	30,305,226	30,603,922
Gross undiscounted claim liability	10,746,955	11,276,259
Discount, gross claim liability	(2,065,190)	(2,452,448)
Gross claim liability before all subrogation and before reinsurance	8,681,765	8,823,811
Less:
Gross RMBS subrogation	(2,235,231)	(2,215,849)
Discount, RMBS subrogation	10,936	9,251
Discounted RMBS subrogation, before reinsurance	(2,224,295)	(2,206,598)
Less:
Gross other subrogation	(835,939)	(846,699)
Discount, other subrogation	87,723	91,313
Discounted other subrogation, before reinsurance	(748,216)	(755,386)
Gross claim liability, net of all subrogation and discounts, before reinsurance	5,709,254	5,861,827
Less: Unearned premium reserves	(495,006)	(502,984)
Plus: Loss adjustment expenses reserves	99,685	111,391
Claim liability reported on Balance Sheet, before reinsurance	5,313,933	5,470,234
Reinsurance recoverable reported on Balance Sheet	111,442	121,249
I/SL [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	27	18
Remaining weighted-average contract period (in years)	12 years	13 years
Gross insured contractual payments outstanding:
Principal	760,825	834,708
Interest	415,417	506,903
Total	1,176,242	1,341,611
Gross undiscounted claim liability	5,408	7,447
Discount, gross claim liability	(747)	(1,225)
Gross claim liability before all subrogation and before reinsurance	4,661	6,222
Less:
Gross claim liability, net of all subrogation and discounts, before reinsurance	4,661	6,222
Less: Unearned premium reserves	(3,195)	(4,060)
Claim liability reported on Balance Sheet, before reinsurance	1,466	2,162
Reinsurance recoverable reported on Balance Sheet	55	146
IA [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	29	23
Remaining weighted-average contract period (in years)	13 years	19 years
Gross insured contractual payments outstanding:
Principal	964,929	1,125,284
Interest	485,353	871,751
Total	1,450,282	1,997,035
Gross undiscounted claim liability	17,697	54,398
Discount, gross claim liability	(1,456)	(6,726)
Gross claim liability before all subrogation and before reinsurance	16,241	47,672
Less:
Gross claim liability, net of all subrogation and discounts, before reinsurance	16,241	47,672
Less: Unearned premium reserves	(9,270)	(22,901)
Plus: Loss adjustment expenses reserves	11	11
Claim liability reported on Balance Sheet, before reinsurance	6,982	24,782
Reinsurance recoverable reported on Balance Sheet	872	2,271
II [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	66	52
Remaining weighted-average contract period (in years)	16 years	17 years
Gross insured contractual payments outstanding:
Principal	4,057,893	3,464,420
Interest	2,765,425	2,130,271
Total	6,823,318	5,594,691
Gross undiscounted claim liability	245,484	221,321
Discount, gross claim liability	(29,272)	(32,630)
Gross claim liability before all subrogation and before reinsurance	216,212	188,691
Less:
Gross other subrogation	(22,213)	(20,367)
Discount, other subrogation	9,694	9,522
Discounted other subrogation, before reinsurance	(12,519)	(10,845)
Gross claim liability, net of all subrogation and discounts, before reinsurance	203,693	177,846
Less: Unearned premium reserves	(108,203)	(95,550)
Plus: Loss adjustment expenses reserves	2,275	2,257
Claim liability reported on Balance Sheet, before reinsurance	97,765	84,553
Reinsurance recoverable reported on Balance Sheet	2,795	2,273
III [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	70	76
Remaining weighted-average contract period (in years)	19 years	19 years
Gross insured contractual payments outstanding:
Principal	5,232,627	5,597,387
Interest	2,168,384	2,331,222
Total	7,401,011	7,928,609
Gross undiscounted claim liability	2,616,809	3,029,891
Discount, gross claim liability	(1,006,627)	(1,299,032)
Gross claim liability before all subrogation and before reinsurance	1,610,182	1,730,859
Less:
Gross RMBS subrogation	(2,513)	(4,516)
Discount, RMBS subrogation	9	15
Discounted RMBS subrogation, before reinsurance	(2,504)	(4,501)
Less:
Gross other subrogation	(117,755)	(116,145)
Discount, other subrogation	33,024	36,125
Discounted other subrogation, before reinsurance	(84,731)	(80,020)
Gross claim liability, net of all subrogation and discounts, before reinsurance	1,522,947	1,646,338
Less: Unearned premium reserves	(275,241)	(280,245)
Plus: Loss adjustment expenses reserves	1,462	1,658
Claim liability reported on Balance Sheet, before reinsurance	1,249,168	1,367,751
Reinsurance recoverable reported on Balance Sheet	110,712	119,795
IV [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	171	169
Remaining weighted-average contract period (in years)	11 years	11 years
Gross insured contractual payments outstanding:
Principal	10,993,947	11,184,943
Interest	2,460,360	2,556,968
Total	13,454,307	13,741,911
Gross undiscounted claim liability	7,861,495	7,963,137
Discount, gross claim liability	(1,027,085)	(1,112,829)
Gross claim liability before all subrogation and before reinsurance	6,834,410	6,850,308
Less:
Gross RMBS subrogation	(2,232,718)	(2,211,333)
Discount, RMBS subrogation	10,927	9,236
Discounted RMBS subrogation, before reinsurance	(2,221,791)	(2,202,097)
Less:
Gross other subrogation	(695,971)	(710,187)
Discount, other subrogation	45,005	45,666
Discounted other subrogation, before reinsurance	(650,966)	(664,521)
Gross claim liability, net of all subrogation and discounts, before reinsurance	3,961,653	3,983,690
Less: Unearned premium reserves	(99,097)	(100,228)
Plus: Loss adjustment expenses reserves	95,937	107,465
Claim liability reported on Balance Sheet, before reinsurance	3,958,493	3,990,927
Reinsurance recoverable reported on Balance Sheet	(2,992)	(3,236)
V [Member]
Schedule of Insured Financial Obligations with Credit Deterioration [Line Items]
Number of policies	1	1
Remaining weighted-average contract period (in years)	6 years	6 years
Gross insured contractual payments outstanding:
Principal	47	47
Interest	19	18
Total	66	65
Gross undiscounted claim liability	62	65
Discount, gross claim liability	(3)	(6)
Gross claim liability before all subrogation and before reinsurance	59	59
Less:
Gross claim liability, net of all subrogation and discounts, before reinsurance	59	59
Claim liability reported on Balance Sheet, before reinsurance	$ 59	$ 59