Derivative Instruments - Summary of Gross Principal Notional Outstanding for CDS Contracts (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Ambac Rating
Notional outstanding	$ 2,202,760	$ 2,776,103
Successor Ambac [Member]
Ambac Rating
Notional outstanding	2,202,760	2,776,103
Other Derivatives [Member] | Successor Ambac [Member]
Ambac Rating
Notional outstanding	2,202,760	2,776,103
Other Derivatives [Member] | Successor Ambac [Member] | AAA Rating [Member]
Ambac Rating
Notional outstanding	0	24,034
Other Derivatives [Member] | Successor Ambac [Member] | AA Rating [Member]
Ambac Rating
Notional outstanding	1,049,616	1,412,096
Other Derivatives [Member] | Successor Ambac [Member] | A Rating [Member]
Ambac Rating
Notional outstanding	43,160	235,917
Other Derivatives [Member] | Successor Ambac [Member] | BBB Rating [Member]
Ambac Rating
Notional outstanding	827,450	826,175
Other Derivatives [Member] | Successor Ambac [Member] | Below Investment Grade Rating [Member]
Ambac Rating
Notional outstanding	282,534	277,881
CLO [Member] | Successor Ambac [Member]
Ambac Rating
Notional outstanding	841,744	1,337,737
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member]
Ambac Rating
Notional outstanding	841,744	1,337,737
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member] | AAA Rating [Member]
Ambac Rating
Notional outstanding	0	0
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member] | AA Rating [Member]
Ambac Rating
Notional outstanding	841,744	1,209,071
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member] | A Rating [Member] [Member]
Ambac Rating
Notional outstanding	0	128,666
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member] | BBB Rating [Member]
Ambac Rating
Notional outstanding
CLO [Member] | Other Derivatives [Member] | Successor Ambac [Member] | Below Investment Grade Rating [Member]
Ambac Rating
Notional outstanding
Other [Member] | Successor Ambac [Member]
Ambac Rating
Notional outstanding	1,361,016	1,438,366
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member]
Ambac Rating
Notional outstanding	1,361,016	1,438,366
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member] | AAA Rating [Member]
Ambac Rating
Notional outstanding	0	24,034
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member] | AA Rating [Member]
Ambac Rating
Notional outstanding	207,872	203,025
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member] | A Rating [Member]
Ambac Rating
Notional outstanding	43,160	107,251
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member] | BBB Rating [Member]
Ambac Rating
Notional outstanding	827,450	826,175
Other [Member] | Other Derivatives [Member] | Successor Ambac [Member] | Below Investment Grade Rating [Member]
Ambac Rating
Notional outstanding	$ 282,534	$ 277,881