Acquisitions EnTrustPermal Restructuring (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended	12 Months Ended		15 Months Ended
		Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2016	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2017	Dec. 31, 2015
EnTrust Capital [Member]
Restructuring Cost and Reserve [Line Items]
Revenues			$ 39,206		$ 84,472
EnTrustPermal [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring				$ (24,035)	(35,290)
Restructuring and Related Cost, Cost Incurred to Date			82,982		82,982		$ 82,982
Restructuring and Related Cost, Incurred Cost			3,023		39,686
Restructuring Reserve			15,802	17,527	15,802		15,802		$ 0
Restructuring Reserve, Settled without Cash	[1]			1,734	6,121		7,855
Restructuring Reserve, Accrual Adjustment				41,562	33,565
EnTrustPermal [Member] | Minimum [Member] | Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 3,000				$ 8,000		$ 91,000
EnTrustPermal [Member] | Maximum [Member] | Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 4,000				$ 10,000		$ 93,000
EnTrustPermal [Member] | Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring				(21,938)	(24,404)
Restructuring and Related Cost, Cost Incurred to Date			57,742		57,742		57,742
Restructuring Reserve			8,084	9,643	8,084		8,084		0
Restructuring Reserve, Settled without Cash	[1]			591	2,725		3,316
Restructuring Reserve, Accrual Adjustment				31,581	22,845
EnTrustPermal [Member] | Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring				(2,097)	(10,886)
Restructuring and Related Cost, Cost Incurred to Date			25,240		25,240		25,240
Restructuring Reserve			7,718	7,884	7,718		7,718		$ 0
Restructuring Reserve, Settled without Cash	[1]			1,143	3,396		4,539
Restructuring Reserve, Accrual Adjustment	[2]			9,981	10,720
EnTrustPermal [Member] | Commitments Related to Vacated Space that Remains Vacant [Member]
Restructuring Cost and Reserve [Line Items]
Valuation Allowances and Reserves, Balance			$ 9,069	$ 7,212	9,069		$ 9,069
EnTrust Capital [Member]
Restructuring Cost and Reserve [Line Items]
Business Combination, Acquisition Related Costs					$ 7,031

[1] Includes stock-based compensation expense and accelerated fixed asset depreciation.

[2] Includes lease loss reserve for space permanently abandoned of $9,069 for the nine months ended December 31, 2016, and $7,212 for the year ended March 31, 2016.