Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Detail) - Successor [Member] - USD ($)
$ in Thousands

3 Months Ended

6 Months Ended

12 Months Ended

Jun. 30, 2018

Jun. 30, 2017

Jun. 30, 2018

Jun. 30, 2017

Dec. 31, 2017

Dec. 31, 2016

Mar. 31, 2018

Mar. 31, 2017

Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

$ 11,110,155

$ 12,044,498

$ 11,110,155

$ 12,044,498

$ 12,561,185

$ 11,369,112

$ 11,950,737

$ 11,588,457

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

37,791

90,285

(48,387)

343,534

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(691,566)

412,299

(313,415)

602,225

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

25,930

35,781

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

79,319

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(181,498)

(72,473)

(1,083,919)

248,913

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

22,078

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

(5,309)

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

37,418

23,931

(84,050)

269,852

Fair Value, Inputs, Level 3 [Member] | Investments [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

68,802

765,682

68,802

765,682

808,557

762,703

77,630

721,624

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

282

16,479

35,466

26,298

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(3,514)

10,812

(56,022)

17,097

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

25,930

35,781

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

79,319

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(287)

(9,163)

(713,890)

18,956

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

22,078

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

(5,309)

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

Fair Value, Inputs, Level 3 [Member] | European ABS Transactions [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Of Consolidated Variable Interest Entity Debt Obligations Valued Using Unobservable Inputs By Asset Class

2,517,638

2,757,688

Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

5,255

6,691

5,255

6,691

5,979

7,382

5,621

7,039

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(366)

(348)

(724)

(691)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(366)

(348)

(724)

(691)

Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

45,613

52,729

45,613

52,729

60,808

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(12,057)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(3,138)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(12,254)

Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

11,301,298

Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

(2,804,218)

Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

(100,282)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

51,298

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(101,713)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

3,914

Derivative Financial Instruments, Liabilities [Member] | Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

45,613

52,729

45,613

52,729

49,908

(102,588)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(2,682)

54,115

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(1,613)

101,202

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(2,773)

4,240

Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

2,722,316

Variable Interest Entity, Primary Beneficiary [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(71,072)

266,629

Variable Interest Entity, Primary Beneficiary [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

10,658,963

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

378,390

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

586,391

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

322,446

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

378,390

Variable Interest Entity, Primary Beneficiary [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

2,622,566

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(31,454)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

147,131

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

15,927

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(31,454)

Variable Interest Entity, Primary Beneficiary [Member] | Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

10,751,199

11,529,384

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(175,122)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(248,703)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(354,360)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(175,122)

Variable Interest Entity, Primary Beneficiary [Member] | Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member] | Loans Receivable [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

10,751,199

11,301,298

10,751,199

11,301,298

11,558,331

11,015,305

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

27,466

32,198

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(672,595)

402,842

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(162,003)

(149,047)

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

27,466

32,198

Variable Interest Entity, Primary Beneficiary [Member] | Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

(2,517,638)

(2,804,218)

(2,517,638)

(2,804,218)

(2,757,688)

$ (2,582,220)

(2,696,516)

(2,716,642)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

17,228

14,100

177,213

(80,307)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

161,650

(102,138)

57,773

(148,394)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

462

5,064

(6,703)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Into Level Three

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

17,228

14,100

177,213

(80,307)

Variable Interest Entity, Primary Beneficiary [Member] | Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

2,756,924

$ 2,914,145

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(73,163)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(66,463)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Purchases

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Sales

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(17,595)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Transfers Out Of Level Three

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

(73,163)

Variable Interest Entity, Primary Beneficiary [Member] | Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]

Fair Value Inputs, Liabilities, Quantitative Information [Line Items]

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability

2,756,924

2,722,316

$ 2,756,924

$ 2,722,316

$ 2,955,763

$ 2,663,719

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Earnings

(4,137)

(26,259)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Gain Loss Included In Other Comprehensive Income Loss

(177,107)

100,783

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Settlements

(17,595)

(15,927)

Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held

$ (4,137)

$ (26,259)