Acquisitions Martin Currie Acquisition (Details) £ in Thousands, $ in Thousands	3 Months Ended			6 Months Ended
	Sep. 30, 2015 USD ($)	Dec. 31, 2014 GBP (£)	Dec. 31, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2015 GBP (£)	Sep. 30, 2015 USD ($)	Oct. 01, 2014 USD ($)
Martin Currie [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		£ 125,000	$ 202,577
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High					£ 325,000	$ 491,406
Business Combination, Contingent Consideration, Liability						71,499	$ 75,211
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	$ 1,385
Martin Currie [Member]
Business Acquisition [Line Items]
Total Operating Revenues	$ 13,904			$ 27,841
Other Current Liabilities [Member] | Martin Currie [Member]
Business Acquisition [Line Items]
Business Combination, Contingent Consideration, Liability						$ 10,648