Variable Interest Entities (Details) - Variable Interest Entity, Primary Beneficiary [Member] - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Non-controlling interest in equity of consolidated subsidiaries	$ 109.9	$ 112.1
Variable Interest Entity, Consolidated, Carrying Amount, Assets	206.8	223.4
New Ocean Capital Management Ltd [Member]
Variable Interest Entity [Line Items]
Non-controlling interest in equity of consolidated subsidiaries	$ 0.5	$ 1.0