Derivative Instruments - Summarize Information by Major Category of CDS Contracts (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014 Transactions	Dec. 31, 2013 Transactions
Summary of information by major category of CDS contracts
Gross principal notional outstanding	$ 2,202,760	$ 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 8 months 15 days	3 years 7 months 6 days
Gross principal notional outstanding	2,202,760	2,776,103
Successor Ambac [Member] | Credit Derivatives [Member]
Summary of information by major category of CDS contracts
Net derivative liabilities at fair value	89,651	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)	1 year 10 months 15 days	2 years 1 month 15 days
Gross principal notional outstanding	841,744	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	3,811	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)	4 years 320 days	5 years 0 months 15 days
Gross principal notional outstanding	1,361,016	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	$ 85,840	$ 86,329