Fair Value Measurements - Summary of Gains and Losses (Realized and Unrealized) Relating to Level 3 Assets and Liabilities Included in Earnings (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period			$ 323,192	$ 1,226,106
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held			323,192	1,226,106
Net Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	$ 8,330	$ 15,804	34,628
Total gains or losses included in earnings for the period				42,823
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	0	0	0	0
Realized Gains Or (Losses) and Other Settlements On Credit Derivative Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	134	226	1,467	711
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	0	0	0	0
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	45	1,507	6,388	17,843
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	37	1,503	(75)	17,778
Interest Rate Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	1,852	(13,953)	45,474	(41,804)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	1,852	(13,953)	5,715	(41,804)
Income Loss On Variable Interest Entities [Member] | Variable Interest Entity [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	56,562	619,439
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	56,562	619,439
Other Income or (Loss) [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	(354)	(958)	(1,045)	(967)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	$ (354)	$ (958)	$ (1,045)	$ (967)