Segment Operating Results - (Footnotes) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Information [Line Items]
Other Revenue, net	$ (1,037)	$ (1,342)
Total Other Expenses	(18,979)	35,110
Investment Banking [Member]
Segment Reporting Information [Line Items]
Other Revenue, net	(1,168)	(913)
Interest expense on Notes Payable, Subordinated Borrowing and Line of Credit	2,581	1,478
Amortization of LP Units / Interests and Certain Other Awards	(21,371)	31,759
Fair Value of Contingent Consideration	0	106
Intangible Asset and Other Amortization	2,392	3,163
Total Other Expenses	(18,979)	35,028
Investment Management [Member]
Segment Reporting Information [Line Items]
Other Revenue, net	131	(429)
Interest expense on Notes Payable, Subordinated Borrowing and Line of Credit		670
Intangible Asset and Other Amortization	0	82
Total Other Expenses	$ 0	$ 82