Acquisitions EnTrustPermal Restructuring (Details) - EnTrustPermal [Member] - USD ($) $ in Thousands		3 Months Ended			12 Months Ended		18 Months Ended
		Jun. 30, 2017	Mar. 31, 2016		Mar. 31, 2017		Jun. 30, 2017	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Valuation Allowances and Reserves, Balance			$ 7,212		$ 9,069
Payments for Restructuring		$ 5,159	24,035		41,619
Restructuring Reserve		5,832	17,527		9,874		$ 5,832	$ 0
Restructuring Reserve, Accrual Adjustment		1,117	41,562		33,966
Restructuring Reserve, Settled without Cash	[1]	1,445	1,734		7,819		10,998
Restructuring and Related Cost, Cost Incurred to Date		87,643					87,643
Restructuring and Related Cost, Incurred Cost		2,562
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring		4,118	21,938		29,211
Restructuring Reserve		128	9,643		3,323		128	0
Restructuring Reserve, Accrual Adjustment		923	31,581		22,891
Restructuring Reserve, Settled without Cash	[1]	1,441	591		4,423		6,455
Restructuring and Related Cost, Cost Incurred to Date		61,850					61,850
Other Restructuring [Member]
Restructuring Cost and Reserve [Line Items]
Payments for Restructuring		1,041	2,097		12,408
Restructuring Reserve		5,704	7,884		6,551		5,704	$ 0
Restructuring Reserve, Accrual Adjustment		194	9,981	[2]	11,075	[2]
Restructuring Reserve, Settled without Cash	[1]	4	$ 1,143		$ 3,396		4,543
Restructuring and Related Cost, Cost Incurred to Date		25,793					25,793
Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost		3,000					3,000
Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost		$ 4,000					$ 4,000

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

[2] (1) Includes lease loss reserve for space permanently abandoned of $9,069 for the year ended March 31, 2017, and $7,212 for the year ended March 31, 2016.