Acquisitions EnTrustPermal Restructuring (Details) - EnTrustPermal [Member] - USD ($) $ in Thousands		3 Months Ended		6 Months Ended	12 Months Ended	15 Months Ended
		Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2016	Mar. 31, 2017	Mar. 31, 2017	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring		$ (8,356)	$ (24,035)
Restructuring and Related Cost, Cost Incurred to Date		67,559		$ 67,559
Restructuring and Related Cost, Incurred Cost		24,263
Restructuring Reserve		29,924	17,527	29,924			$ 0
Restructuring Reserve, Settled without Cash	[1]	3,510	1,734	5,244
Restructuring Reserve, Accrual Adjustment		20,753	41,562
Minimum [Member] | Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					$ 23,000	$ 91,000
Maximum [Member] | Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges					$ 32,000	$ 100,000
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring		(6,995)	(21,938)
Restructuring and Related Cost, Cost Incurred to Date		47,158		47,158
Restructuring Reserve		16,534	9,643	16,534			0
Restructuring Reserve, Settled without Cash	[1]	1,100	591	1,691
Restructuring Reserve, Accrual Adjustment		13,886	31,581
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring		(1,361)	(2,097)
Restructuring and Related Cost, Cost Incurred to Date		20,401		20,401
Restructuring Reserve		13,390	7,884	13,390			$ 0
Restructuring Reserve, Settled without Cash	[1]	2,410	1,143	3,553
Restructuring Reserve, Accrual Adjustment	[2]	6,867	9,981
Commitments Related to Vacated Space that Remains Vacant [Member]
Restructuring Cost and Reserve [Line Items]
Valuation Allowances and Reserves, Balance		$ 6,558	$ 7,212	$ 6,558

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

[2] (1) Includes lease loss reserve for space permanently abandoned of $6,558 for the three months ended June 30, 2016, and $7,212 for the year ended March 31, 2016.