Derivative Instruments - Summary of Gross Fair Values of Individual Derivative Instruments (Detail) - Successor [Member] - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	$ 56,671	$ 73,826
Gross Amounts of Recognized Liabilities, Derivative Liabilities	67,809	83,409
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	161	627
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	161	627
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	56,510	73,199
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	67,648	82,782
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	65,563	81,260
Net Amount, Derivative Assets	56,510	73,199
Net Amount, Derivative Liabilities	2,085	1,522
Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	60,403	54,877
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,992,227	2,205,264
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	60,403	54,877
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,992,227	2,205,264
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	60,403	54,877
Net Amount, Derivative Liabilities	1,992,227	2,205,264
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	56,147	73,826
Gross Amounts of Recognized Liabilities, Derivative Liabilities	66,483	81,495
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	161	627
Gross Amounts Offset in the Consolidated Balance Sheet, Derivative Assets / Liabilities	161	627
Net Amounts of Assets Presented in the Consolidated Balance Sheet, Derivative Assets	55,986	73,199
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	66,322	80,868
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities	65,563	79,912
Net Amount, Derivative Assets	55,986	73,199
Net Amount, Derivative Liabilities	759	956
Interest Rate Swap [Member] | Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,992,227	2,205,264
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities	1,992,227	2,205,264
Net Amount, Derivative Liabilities	1,992,227	2,205,264
Futures Contracts [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	524
Gross Amounts of Recognized Liabilities, Derivative Liabilities		1,348
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	524
Net Amounts of Liabilities Presented in the Consolidated Balance Sheet, Derivative Liabilities		1,348
Gross Amount of Collateral Received/Pledged Not Offset in the Consolidated Balance Sheet, Derivative Liabilities		1,348
Net Amount, Derivative Assets	524
Net Amount, Derivative Liabilities		0
Credit Derivatives [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities, Derivative Liabilities	1,326	566
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	1,326	566
Net Amount, Derivative Liabilities	1,326	566
Currency Swaps [Member] | Variable Interest Entity [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets, Derivative Assets	60,403	54,877
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	60,403	54,877
Net Amount, Derivative Assets	$ 60,403	$ 54,877