Acquisitions (Details) - USD ($) $ in Thousands	Jun. 20, 2014	Jun. 30, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill		$ 3,044,807	$ 3,044,807
Redeemable non-controlling interest		$ 16,504	$ 16,504
CPH Capital Fondsmaeglerselskab A/S [Member]
Business Acquisition [Line Items]
Ownership percentage	82.00%
Assets under management	$ 3,000,000
Cash paid	64,400
Net contingent consideration payable	9,400
Goodwill	58,100
Definite-lived intangible assets	24,100
Indefinite-lived intangible assets acquired	3,500
Redeemable non-controlling interest	$ 16,500