Fair Value Measurements - Summary of Changes in Level 3 Fair Value Category (Detail) - Successor [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Investment by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	$ 262,732	$ 66,923	$ 198,201	$ 67,783
Additions of VIEs consolidated			0	0
Included in earnings	6,908	422	12,637	841
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	(38,617)	(124)	(44,323)	(341)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	150,348		234,852
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(1,039)	(869)	(21,035)	(1,723)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three				(208)
Balance, end of period	380,332	66,352	380,332	66,352
Derivatives by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	(230,201)	(202,482)	(215,346)	(186,934)
Included in earnings	14,489	(25,959)	568	(40,208)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	8,185	9,780	7,251	8,481
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	88,218	0	88,218	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Deconsolidation of VIEs			0	0
Balance, end of period	(119,309)	(218,661)	(119,309)	(218,661)
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	(14,081)	27,284	1,933	42,315
Credit Derivative [Member] | Derivatives by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	(76,377)	(87,715)	(73,459)	(94,322)
Included in earnings	10,294	(1,219)	7,795	6,163
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(407)	(717)	(826)	(1,492)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	(66,490)	(89,651)	(66,490)	(89,651)
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	(9,886)	2,544	(5,294)	(4,056)
Interest Rate Swaps [Member] | Derivatives by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	(153,824)	(114,767)	(141,887)	(92,612)
Included in earnings	4,195	(24,740)	(7,227)	(46,371)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	8,592	10,497	8,077	9,973
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	88,218	0	88,218	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	(52,819)	(129,010)	(52,819)	(129,010)
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	(4,195)	24,740	7,227	46,371
Residential Mortgage-Backed Securities [Member] | Investment by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	262,732	0	194,393	0
Additions of VIEs consolidated			0	0
Included in earnings	6,908	0	12,656	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	(38,617)		(44,037)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	150,348		234,852
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(1,039)	0	(17,532)	0
Balance, end of period	380,332		380,332
Asset-backed Securities [Member] | Investment by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	63,367	0	64,073
Additions of VIEs consolidated			0	0
Included in earnings	0	446	0	889
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	(343)	0	(638)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	(869)	0	(1,723)
Balance, end of period	0	62,601	0	62,601
Corporate Debt Securities [Member] | Investment by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	3,556	3,808	3,502
Additions of VIEs consolidated			0	0
Included in earnings	0	(24)	(19)	(48)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	219	(286)	297
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements			(3,503)
Balance, end of period	0	3,751	0	3,751
Interest Rate Swaps [Member] | Derivatives by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deconsolidation of VIEs			0	0
Credit Derivative [Member] | Derivatives by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Deconsolidation of VIEs			0	0
US Government Agencies Debt Securities [Member] | Investment by Class [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	0	0	0	208
Additions of VIEs consolidated			0	0
Included in earnings	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three				(208)
Level 3 [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	13,504,326	14,409,383	13,845,454	14,253,705
Included in earnings	(573,055)	192,134	(218,493)	364,672
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	731,700	365,973	100,485	452,772
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	150,348	0	234,852	70,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	45,239	50,447	194,218	223,898
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	88,218	0	88,218	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	208
Balance, end of period	13,856,298	14,917,043	13,856,298	14,917,043
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	580,371	(190,387)	233,631	(359,729)
Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	(230,201)	(202,482)	(215,346)	(186,934)
Included in earnings	14,489	(25,959)	568	(40,208)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	(8,185)	(9,780)	(7,251)	(8,481)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	88,218	0	88,218	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	(119,309)	(218,661)	(119,309)	(218,661)
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	(14,081)	27,284	1,933	42,315
Level 3 [Member] | Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	262,732	66,923	198,201	67,783
Included in earnings	6,908	422	12,637	841
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	(38,617)	(124)	(44,323)	(341)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	150,348	0	234,852	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	1,039	869	21,035	1,723
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	208
Balance, end of period	380,332	66,352	380,332	66,352
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	0	0	0	0
Level 3 [Member] | Other Assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	10,036	13,122	12,036	13,384
Included in earnings	(332)	(340)	(627)	(602)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	0	1,705	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	9,704	12,782	9,704	12,782
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	332	340	627	602
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date			231,071	(402,646)
Variable Interest Entity, Primary Beneficiary [Member] | Level 3 [Member] | Long-Term Debt [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	(2,032,099)	(1,284,394)	(1,263,664)	(1,514,605)
Included in earnings	(23,091)	(61,028)	(863,089)	(251,990)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	(111,636)	(29,627)	(44,011)	(38,248)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	0	(3,938)	(429,794)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	(2,166,826)	(1,375,049)	(2,166,826)	(1,375,049)
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	23,091	61,028	863,089	248,852
Variable Interest Entity, Primary Beneficiary [Member] | Level 3 [Member] | Loans Receivable [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	12,789,201	13,269,452	12,371,177	13,398,895
Included in earnings	(453,769)	204,722	657,158	526,569
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	722,169	328,415	159,548	408,217
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	70,000
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	52,385	59,358	182,667	660,450
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	13,005,216	13,743,231	13,005,216	13,743,231
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	453,769	(204,722)	(657,158)	(521,436)
Variable Interest Entity, Primary Beneficiary [Member] | Level 3 [Member] | Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of period	2,704,657	2,546,762	2,743,050	2,475,182
Included in earnings	(117,260)	74,317	(25,140)	130,062
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss	159,784	67,309	29,271	83,144
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Issues	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three	0	0	0	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three	0	0	0	0
Balance, end of period	2,747,181	2,688,388	2,747,181	2,688,388
The amount of total gains/(losses) included in earnings attributable to the change in unrealized gains or losses relating to assets and liabilities still held at the reporting date	$ 117,260	$ (74,317)	$ 25,140	$ (130,062)