Investments of Operating Entities and Consolidated Funds - Other Investments - Quarterly (Details) - USD ($) $ in Thousands	Sep. 30, 2017		Dec. 31, 2016
Investment Holdings [Line Items]
Other investments	$ 141,180		$ 157,279
Portfolio Funds, at fair value
Investment Holdings [Line Items]
Other investments	98,491	[1]	120,023	[2]
Equity Method Investments
Investment Holdings [Line Items]
Other investments	42,370		36,991
Lehman claims, at fair value
Investment Holdings [Line Items]
Other investments	$ 319		$ 265

[1] In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.

[2] In accordance with US GAAP, certain investments that are measured at fair value using the net asset value per share (or its equivalent) as a practical expedient have not been classified in the fair value hierarchy. The fair value amounts presented in this table are intended to permit reconciliation of the fair value hierarchy to the amounts presented in the condensed consolidated statement of financial condition.