Fair Value Measurements - Summary of Gains and Losses (Realized and Unrealized) Relating to Level 3 Assets and Liabilities Included in Earnings (Detail) - USD ($) $ in Thousands	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Successor [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		$ (636,043)	$ (590,327)	$ 1,256,740
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		(655,964)	(579,620)	1,261,927
Predecessor [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	$ 1,146,256
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	1,146,256
Net Investment Income [Member] | Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period		1,870	30,083	11,057
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		0	0	0
Net Investment Income [Member] | Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	(33)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	0
Realized Gains Or (Losses) and Other Settlements On Credit Derivative Contracts [Member] | Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period		9,778	2,785	3,043
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		0	0	0
Realized Gains Or (Losses) and Other Settlements On Credit Derivative Contracts [Member] | Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	3,444
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	0
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member] | Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period		183,091	38,916	20,863
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		66,639	(850)	15,789
Unrealized Gains Or (Losses) On Credit Derivative Contracts [Member] | Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	(63,828)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	(63,840)
Interest Rate Swap [Member] | Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period		24,797	(25,130)	(69,298)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		24,797	(25,130)	(69,298)
Interest Rate Swap [Member] | Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	(28,162)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	(28,162)
Other Income or (Loss) [Member] | Successor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period		(677)	(1,635)	(1,348)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held		$ (677)	$ (1,635)	$ (1,348)
Other Income or (Loss) [Member] | Predecessor [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Total gains or losses included in earnings for the period	(496)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held	$ (496)