Derivative Instruments - Summarize Information by Major Category of CDS Contracts (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014 Transactions	Dec. 31, 2013 Transactions
Summary of information by major category of CDS contracts
Gross principal notional outstanding	$ 2,491,138	$ 2,776,103
Successor Ambac [Member]
Summary of information by major category of CDS contracts
Number of CDS transactions	19	20
Remaining expected weighted-average life of obligations (in years)	3 years 7 months 26 days	3 years 7 months 6 days
Gross principal notional outstanding	2,491,138	2,776,103
Successor Ambac [Member] | Credit Derivatives [Member]
Summary of information by major category of CDS contracts
Net derivative liabilities at fair value	(87,715)	(94,322)
CLO [Member] | Successor Ambac [Member]
Summary of information by major category of CDS contracts
Number of CDS transactions	7	7
Remaining expected weighted-average life of obligations (in years)	2 years 0 months 15 days	2 years 1 month 15 days
Gross principal notional outstanding	1,101,199	1,337,737
CLO [Member] | Successor Ambac [Member] | Credit Derivatives [Member]
Summary of information by major category of CDS contracts
Net derivative liabilities at fair value	(5,847)	(7,993)
Other [Member] | Successor Ambac [Member]
Summary of information by major category of CDS contracts
Number of CDS transactions	12	13
Remaining expected weighted-average life of obligations (in years)	5 years 0 months 15 days	5 years 0 months 15 days
Gross principal notional outstanding	1,389,939	1,438,366
Other [Member] | Successor Ambac [Member] | Credit Derivatives [Member]
Summary of information by major category of CDS contracts
Net derivative liabilities at fair value	$ (81,868)	$ (86,329)