Convertible Debentures - Additional Information (Detail) (USD $)	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Debt Instrument [Line Items]
Interest Expense, Other	$ 115,000us-gaap_InterestExpenseOther	$ 381,000us-gaap_InterestExpenseOther

Interest expense on all other items not previously classified. For example, includes dividends associated with redeemable preferred stock of a subsidiary that is treated as a liability in the parent's consolidated balance sheet.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4D

-URI http://asc.fasb.org/extlink&oid=35706170&loc=SL5624177-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph -4

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

Name:	us-gaap_InterestExpenseOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration