Acquisitions Martin Currie - Other Acquisitions (Details) - USD ($) $ in Thousands		3 Months Ended
		Dec. 31, 2015	Dec. 31, 2016
Business Acquisition [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	[1]		$ 530,399
PK Investments [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross		$ 4,981
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	[1]		$ 2,494
Goodwill		827
Other Fund Management Contracts [Member] | PK Investments [Member]
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Indefinite-Lived Intangible Assets		$ 6,619

[1] Using the applicable exchange rate as of December 31, 2016, for amounts denominated in currencies other than the U.S. dollar.