Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) - Successor [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	$ 78,439	$ 139,581
Gross Amounts of Recognized Liabilities, Derivative Liabilities	92,051	381,125
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	1,152	61,839
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	1,152	61,839
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	77,287	77,742
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	90,899	319,286
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	81,762	156,925
Net Amount, Derivative Assets	77,287	77,742
Net Amount, Derivative Liabilities	9,137	162,361
Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	57,714	80,407
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,088,922	2,078,601
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	57,714	80,407
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	2,088,922	2,078,601
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	0	0
Net Amount, Derivative Assets	57,714	80,407
Net Amount, Derivative Liabilities	2,088,922	2,078,601
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	76,203	139,045
Gross Amounts of Recognized Liabilities, Derivative Liabilities	83,090	365,776
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	1,152	61,839
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	1,152	61,839
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	75,051	77,206
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	81,938	303,937
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	81,762	156,925
Net Amount, Derivative Assets	75,051	77,206
Net Amount, Derivative Liabilities	176	147,012
Interest Rate Swap [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	2,088,922	2,078,601
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	2,088,922	2,078,601
Net Amount, Derivative Liabilities	2,088,922	2,078,601
Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	2,236	536
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	2,236	536
Net Amount, Derivative Assets	2,236	536
Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	8,961	15,349
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	8,961	15,349
Net Amount, Derivative Liabilities	8,961	15,349
Currency Swaps [Member] | Variable Interest Entities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	57,714	80,407
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	57,714	80,407
Net Amount, Derivative Assets	$ 57,714	$ 80,407