Subsequent Event Subsequent Event (Details) - Jun. 30, 2015 - USD ($) $ in Thousands	Total
RARE Infrastructure, Ltd [Member]
Subsequent Event [Line Items]
Assets Under Management	$ 7,600,000
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	15.00%
Consolidated Entity Excluding Consolidated Investment Vehicles Before Eliminations [Member]
Subsequent Event [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	75.00%
Outside Investors
Subsequent Event [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	10.00%