Acquisitions RARE Acquisition (Details) AUD in Thousands, $ in Thousands		3 Months Ended
		Dec. 31, 2015 AUD	Dec. 31, 2015 USD ($)		Oct. 21, 2015 AUD	Oct. 21, 2015 USD ($)		Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Line of Credit Facility, Fair Value of Amount Outstanding			$ 40,000					$ 40,000
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	[1]		617,855
RARE Infrastructure, Ltd [Member]
Business Acquisition [Line Items]
Assets Under Management						$ 6,800,000
Noncontrolling Interest, Ownership Percentage by Parent					75.00%	75.00%
Payments to Acquire Businesses, Gross		AUD 296,000	$ 213,739	[2]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High					AUD 106,000	$ 77,253	[1]
RARE Management Team [Member]
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners					15.00%	15.00%
Outside Investors
Business Acquisition [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners					10.00%	10.00%

[1] Using the applicable exchange rate as of December 31, 2015 for amounts denominated in currencies other than the U.S. dollar.

[2] (1)Subject to prospective adjustments, including for amounts ultimately realized and adjustments provided for in the share purchase agreement.