Investments in Merchant Banking Funds - Carrying Value of Investments in Merchant Banking Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Investments in and Advances to Affiliates [Line Items]
Investments in merchant banking funds	$ 3,451	$ 4,173
GCP I
Investments in and Advances to Affiliates [Line Items]
Investments in merchant banking funds	1,019	1,600
GCP II
Investments in and Advances to Affiliates [Line Items]
Investments in merchant banking funds	784	907
Investment in other merchant banking funds
Investments in and Advances to Affiliates [Line Items]
Investments in merchant banking funds	$ 1,648	$ 1,666

Total investments in (A) an entity in which the entity has significant influence, but does not have control, (B) subsidiaries that are not required to be consolidated and are accounted for using the equity and or cost method, and (C) an entity in which the reporting entity shares control of the entity with another party or group. Includes long-term advances receivable from a party that is affiliated with the reporting entity by means of direct or indirect ownership.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Name:	us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant