Derivative Instruments - Summary of Gross Principal Notional Outstanding for CDS Contracts (Detail) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 1,447,939	$ 1,529,759
Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	1,447,939	1,529,759
Other Derivatives [Member] | Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	1,447,939	1,529,759
Other Derivatives [Member] | Successor [Member] | AAA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
Other Derivatives [Member] | Successor [Member] | AA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	672,877	767,603
Other Derivatives [Member] | Successor [Member] | A Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	9,322	43,160
Other Derivatives [Member] | Successor [Member] | BBB Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	499,289	448,249
Other Derivatives [Member] | Successor [Member] | Below Investment Grade Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	266,451	270,747
CLO [Member] | Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	433,555	549,923
CLO [Member] | Other Derivatives [Member] | Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	433,555	549,923
CLO [Member] | Other Derivatives [Member] | Successor [Member] | AAA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
CLO [Member] | Other Derivatives [Member] | Successor [Member] | AA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	433,555	549,923
CLO [Member] | Other Derivatives [Member] | Successor [Member] | A Rating [Member] [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
CLO [Member] | Other Derivatives [Member] | Successor [Member] | BBB Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
Other [Member] | Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	1,014,384	979,836
Other [Member] | Other Derivatives [Member] | Successor [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	1,014,384	979,836
Other [Member] | Other Derivatives [Member] | Successor [Member] | AAA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	0	0
Other [Member] | Other Derivatives [Member] | Successor [Member] | AA Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	239,322	217,680
Other [Member] | Other Derivatives [Member] | Successor [Member] | A Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	9,322	43,160
Other [Member] | Other Derivatives [Member] | Successor [Member] | BBB Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	499,289	448,249
Other [Member] | Other Derivatives [Member] | Successor [Member] | Below Investment Grade Rating [Member]
Notional Disclosures [Abstract]
Derivative, Notional Amount	$ 266,451	$ 270,747