Acquisitions QS Investors Acquisition (Details) - USD ($) $ in Thousands		3 Months Ended
		Jun. 30, 2014	Jun. 30, 2016
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	[1]		$ 568,220
QS Investors [Domain]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 11,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			30,000
Contingent payment due on second anniversary of acquisition | QS Investors [Domain]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			10,000
Contingent payment due on fourth anniversary of acquisition [Member] | QS Investors [Domain]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 20,000

[1] Using the applicable exchange rate as of June 30, 2016, for amounts denominated in currencies other than the U.S. dollar.