Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) - Successor [Member] - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	$ 176,727	$ 137,124
Gross Amounts of Recognized Liabilities, Derivative Liabilities	487,499	405,487
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	79,168	52,129
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	79,168	52,129
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	97,559	84,995
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	408,331	353,358
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	208,393	176,386
Net Amount, Derivative Assets	97,559	84,995
Net Amount, Derivative Liabilities	199,938	176,972
Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	48,801	36,862
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,123,608	1,965,265
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	48,801	36,862
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	48,801	36,862
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	2,074,807	1,928,403
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	2,074,807	1,928,403
Interest Rate Swaps [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	176,727	137,015
Gross Amounts of Recognized Liabilities, Derivative Liabilities	465,453	370,944
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	79,168	52,129
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	79,168	52,129
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	97,559	84,886
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	386,285	318,815
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	208,393	176,386
Net Amount, Derivative Assets	97,559	84,886
Net Amount, Derivative Liabilities	177,892	142,429
Interest Rate Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	0
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,123,608	1,965,265
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 Assets Presented in the Consolidated Balance Sheet, Derivative Assets	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	2,123,608	1,965,265
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets	0
Net Amount, Derivative Assets	0
Net Amount, Derivative Liabilities	2,123,608	1,965,265
Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets			$ 109
Gross Amounts of Recognized Liabilities, Derivative Liabilities	117	0
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	117	0
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	0	0
Net Amount, Derivative Assets			$ 109
Net Amount, Derivative Liabilities	117
Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	0	0
Gross Amounts of Recognized Liabilities, Derivative Liabilities	21,929	34,543
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	0
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	21,929	34,543
Net Amount, Derivative Assets	0	0
Net Amount, Derivative Liabilities	21,929	34,543
Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	48,801	36,862
Gross Amounts of Recognized Liabilities, Derivative Liabilities	0	0
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	48,801	36,862
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	48,801	36,862
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	(48,801)	(36,862)
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Assets	0
Net Amount, Derivative Assets	0
Net Amount, Derivative Liabilities	$ (48,801)	$ (36,862)