Information for Financial Instruments on Which Fair Value Option was Elected (Detail) - USD ($)		Jun. 30, 2015	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
Uncollected principal balance on financial instruments that exceeded fair value total		$ (11,700,000)	$ (210,717,000)
Fair value of financial instruments more than one day past due	[1]	330,000	4,369,000
Uncollected principal balance on financial instruments that exceeds fair value more than one day past due	[1]	(4,209,000)	(21,876,000)
Corporate Bonds
Fair Value, Option, Quantitative Disclosures [Line Items]
Uncollected principal balance on financial instruments that exceeded fair value total		(1,441,000)	(7,814,000)
Fair value of financial instruments more than one day past due		0	0
Loans And Receivables
Fair Value, Option, Quantitative Disclosures [Line Items]
Uncollected principal balance on financial instruments that exceeded fair value total		(6,060,000)	(5,323,000)
Fair value of financial instruments more than one day past due			0
Corporate Loans
Fair Value, Option, Quantitative Disclosures [Line Items]
Uncollected principal balance on financial instruments that exceeded fair value total		(4,199,000)	(197,580,000)
Fair value of financial instruments more than one day past due	[1]	330,000	4,369,000
Uncollected principal balance on financial instruments that exceeds fair value more than one day past due	[1]	$ (4,209,000)	$ (21,876,000)

[1] Corporate Loans and Corporate Bonds within CLO assets are classified as past due if contractual payments are more than one day past due.