Fair Value Measurements - Summary of Information about Described Model Inputs Used to Determine Fair Value of Each Class of Credit Derivatives (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Notional outstanding	$ 2,202,760	$ 2,776,103
Successor Ambac [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Notional outstanding	2,202,760	2,776,103
Successor Ambac [Member] | CLO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Notional outstanding	841,744	1,337,737
Weighted average reference obligation price	$ 98.7	$ 98.0
Weighted average life (WAL) in years	1 year 10 months 31 days	2 years 1 month 6 days
Weighted average credit rating	AA	AA
Weighted average relative change ratio	35.60%	35.30%
CVA percentage	6.05%	13.67%
Fair value of derivative liabilities	3,811	7,993
Successor Ambac [Member] | Other [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Notional outstanding	1,273,684	1,291,371
Weighted average reference obligation price	$ 87.9	$ 85.7
Weighted average life (WAL) in years	5 years 0 months 0 days	5 years 4 months 24 days
Weighted average credit rating	BBB-	BBB-
Weighted average relative change ratio	43.50%	43.10%
CVA percentage	15.80%	30.70%
Fair value of derivative liabilities	$ 84,359	$ 84,780