Fair Value Measurements - Additional Information (Details) - Level III [Member] - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Equity Method Investments [Member] | G5 Evercore [Member]
Fair Value Measurements, Nonrecurring [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 11,555
Equity Method Investments [Member] | Atalanta Sosnoff [Member]
Fair Value Measurements, Nonrecurring [Line Items]
Assets, Fair Value Disclosure, Nonrecurring		$ 14,730
Institutional Asset Management [Member] | Goodwill [Member]
Fair Value Measurements, Nonrecurring [Line Items]
Assets, Fair Value Disclosure, Nonrecurring	$ 14,401