Information for Financial Instruments on Which Fair Value Option was Elected (Detail) - USD ($)		Dec. 31, 2015	Dec. 31, 2014
Fair Value, Option, Quantitative Disclosures [Line Items]
(Deficiency) of fair value over uncollected principal		$ (93,217,000)	$ (210,717,000)
Fair value of financial instruments more than one day past due	[1]	1,088,000	4,369,000
(Deficiency) of fair value more than one day past due over uncollected principal	[1]	(5,620,000)	(21,876,000)
Corporate Bonds
Fair Value, Option, Quantitative Disclosures [Line Items]
(Deficiency) of fair value over uncollected principal		(6,046,000)	(7,814,000)
Fair value of financial instruments more than one day past due		0
Corporate Loans
Fair Value, Option, Quantitative Disclosures [Line Items]
(Deficiency) of fair value over uncollected principal		(77,900,000)	(197,580,000)
Fair value of financial instruments more than one day past due	[1]	1,088,000	4,369,000
(Deficiency) of fair value more than one day past due over uncollected principal	[1]	(5,620,000)	(21,876,000)
Debt Securities
Fair Value, Option, Quantitative Disclosures [Line Items]
(Deficiency) of fair value over uncollected principal		(426,000)
Loans and Receivables
Fair Value, Option, Quantitative Disclosures [Line Items]
(Deficiency) of fair value over uncollected principal		(8,845,000)	(5,323,000)
Fair value of financial instruments more than one day past due		$ 0	$ 0

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