Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) - Successor [Member] - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2013
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	$ 137,124	$ 163,683
Gross Amounts of Recognized Liabilities, Derivative Liabilities	405,487	461,610
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	52,129	54,666
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	52,129	54,666
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	84,995	109,017	$ 121,643
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	353,358	406,944	$ 621,645
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	176,386	170,135
Net Amount, Derivative Assets	84,995	109,017
Net Amount, Derivative Liabilities	176,972	236,809
Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	36,862
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,965,265	2,200,163
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	36,862	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	36,862	0
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,928,403	2,200,163
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets	0
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	0	0
Net Amount, Derivative Assets	0
Net Amount, Derivative Liabilities	1,928,403	2,200,163
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	137,015	161,640
Gross Amounts of Recognized Liabilities, Derivative Liabilities	370,944	385,546
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	52,129	54,666
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	52,129	54,666
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	84,886	106,974
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	318,815	330,880
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	176,386	169,573
Net Amount, Derivative Assets	84,886	106,974
Net Amount, Derivative Liabilities	142,429	161,307
Interest Rate Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,965,265	2,133,268
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,965,265	2,133,268
Net Amount, Derivative Liabilities	1,965,265	2,133,268
Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	109
Gross Amounts of Recognized Liabilities, Derivative Liabilities	0	562
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	109
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	0	562
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	0	562
Net Amount, Derivative Assets	109
Net Amount, Derivative Liabilities	0	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	34,543	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	34,543	75,502
Net Amount, Derivative Assets	0	2,043
Net Amount, Derivative Liabilities	34,543	75,502
Currency Swaps [Member]
Derivatives, Fair Value [Line Items]
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	0
Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	36,862
Gross Amounts of Recognized Liabilities, Derivative Liabilities	0	66,895
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	36,862
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	36,862
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	(36,862)	66,895
Net Amount, Derivative Assets	0
Net Amount, Derivative Liabilities	$ (36,862)	$ 66,895