Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) (Successor [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	$ 182,103	$ 163,683
Gross Amounts of Recognized Liabilities, Derivative Liabilities	515,837	461,610
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	68,481	54,666
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	68,481	54,666
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	113,622	109,017
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	447,356	406,944
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets	0	0
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	196,981	170,135
Net Amount, Derivative Assets	113,622	109,017
Net Amount, Derivative Liabilities	250,375	236,809
Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,125,713	2,200,163
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	2,125,713	2,200,163
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	0	0
Net Amount, Derivative Liabilities	2,125,713	2,200,163
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	182,103	161,640
Gross Amounts of Recognized Liabilities, Derivative Liabilities	438,518	385,546
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	68,481	54,666
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	68,481	54,666
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	113,622	106,974
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	370,037	330,880
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	196,039	169,573
Net Amount, Derivative Assets	113,622	106,974
Net Amount, Derivative Liabilities	173,998	161,307
Interest Rate Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,081,082	2,133,268
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	2,081,082	2,133,268
Net Amount, Derivative Liabilities	2,081,082	2,133,268
Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	942
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	942
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	942
Net Amount, Derivative Liabilities	0
Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	0	2,043
Gross Amounts of Recognized Liabilities, Derivative Liabilities	76,377	75,502
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	0	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	0	2,043
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	76,377	75,502
Net Amount, Derivative Assets	0	2,043
Net Amount, Derivative Liabilities	76,377	75,502
Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	44,631	66,895
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	44,631	66,895
Net Amount, Derivative Liabilities	$ 44,631	$ 66,895