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Realized and Net Change in Unrealized Gains (Losses) on Financial Instruments on Financial Instruments on Which Fair Value Option was Elected (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Realized Gains (Losses) | Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments		$ (1,822)		$ (5,914)
Realized Gains (Losses) | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	$ 2,557	7,710	$ 867	(47,140)
Realized Gains (Losses) | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(988)	174	(867)	(2,012)
Realized Gains (Losses) | Senior Secured Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments		(1,822)		(5,914)
Realized Gains (Losses) | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	1,003	7,620	4,276	20,914
Realized Gains (Losses) | Equity and Preferred Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(36)	(468)	(273)	(1,791)
Realized Gains (Losses) | Corporate Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	2,578	384	(2,269)	(64,251)
Net Change In Unrealized Gains (Losses) | Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	34,235	(15,920)	23,997	(55,944)
Net Change In Unrealized Gains (Losses) | Loans and Receivables
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(1,235)		(1,832)
Net Change In Unrealized Gains (Losses) | Debt Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(342)		(342)
Net Change In Unrealized Gains (Losses) | Assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(49,097)	(52,540)	(15,119)	25,580
Net Change In Unrealized Gains (Losses) | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(4,578)	(4,069)	(62)	(375)
Net Change In Unrealized Gains (Losses) | Senior Secured Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments		(38,651)		(134,289)
Net Change In Unrealized Gains (Losses) | Subordinated Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	34,235	22,731	23,997	78,345
Net Change In Unrealized Gains (Losses) | Other
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(305)	(1,032)	(3,636)	18,523
Net Change In Unrealized Gains (Losses) | Equity and Preferred Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	(3,749)	(5,870)	(11,240)	44
Net Change In Unrealized Gains (Losses) | Corporate Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized and net change in unrealized gains (losses) on financial instruments	$ (38,888)	$ (41,569)	$ 1,993	$ 7,388

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef



-Publisher FASB



-Name Accounting Standards Codification



-Topic 825



-SubTopic 10



-Section 50



-Paragraph 30



-Subparagraph (a)



-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

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