A general description of the nature of the existing leasing arrangements of a lessor for all operating leases including, but not limited to: (1) guarantees or indemnities; (2) restrictions imposed by lease arrangements; (3) unusual provisions or conditions; (4) contingent rentals; and (5) lease expiration dates.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6452767&loc=d3e37045-112695

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 23

-Subparagraph c

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_DescriptionOfLessorLeasingArrangementsOperatingLeases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Related Parties - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Related Party Transaction [Line Items]
Sublease agreement			Company agreed to sublease office space to GCP Capital for a period of three to five years beginning in April 2011.
Sublease
Related Party Transaction [Line Items]
Recognized expense related to sublease	$ 0.4	$ 0.4	$ 0.8	$ 0.7
Sublease \| Minimum
Related Party Transaction [Line Items]
Office space lease period			3 years
Sublease \| Maximum
Related Party Transaction [Line Items]
Office space lease period			5 years