Special Purpose Entities, Including Variable Interest Entities - Additional Information (Detail)	4 Months Ended	8 Months Ended	12 Months Ended
	Apr. 30, 2013 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2015 USD ($) Transactions Entity	Dec. 31, 2014 USD ($) Transactions Entity
Variable Interest Entities [Line Items]
variable interest entities deconsolidation gain loss		$ (15,273,000)	$ 572,000	$ 0
Secured Debt			130,571,000
Consolidated VIE assets			14,288,497,000	15,126,110,000
Consolidated VIE liabilities			$ 14,259,776,000	15,085,685,000
Number of RMBS Sold			17
Cash Received From Delaware Trust			$ 146,000,000
Par Value of Securities Placed in Trust			377,837,000
Fair Value of Securities Placed in Trust			396,100,000
Securities Issued by Delaware Trust			146,000,000
Equity Method Investments			25,339,000
Successor [Member]
Variable Interest Entities [Line Items]
Fair value of special purpose entities			$ 8,696,000	$ 12,036,000
Asset-Backed Securities and Utility Obligations [Member]
Variable Interest Entities [Line Items]
Weighted average life			5 years 10 months 7 days
Average rating of assets held by sponsored special purpose entities			BBB
Sponsored Variable Interest Entities [Member]
Variable Interest Entities [Line Items]
Number of individual transactions with special purpose entities | Transactions			15
Number of transactions outstanding with special purpose entities | Transactions				3
Total principal amount of debt outstanding			$ 454,290,000	$ 457,960,000
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entities [Line Items]
Secured Debt			$ 0
Variable Interest Entities [Member] | Successor [Member]
Variable Interest Entities [Line Items]
Amortization Of Variable Interest Entity Intangible Assets		5,015,000
Asset Impairment Charges		$ 76,140,000
Variable Interest Entities [Member] | Predecessor [Member]
Variable Interest Entities [Line Items]
Variable Interest Entity, Initial Consolidation, Gain (Loss)	$ 385,291,000
Fair Value Intangible Assets Initially Recorded Upon Consolidation Of Variable Interest Entity	$ 164,520,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	16 years
Consolidated Entities [Member]
Variable Interest Entities [Line Items]
Number of DeConsolidated Variable Interest Entities		1	2	3
Number of consolidated Variable Interest Entities | Entity			15	15
London Interbank Offered Rate (LIBOR) [Member]
Variable Interest Entities [Line Items]
Interest Rate on Securities Issued by Delaware Trust			2.80%