Variable Interest Entities (Details) - Equity interest attributable to third party investors in New Ocean - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Non-controlling interest in consolidated subsidiaries	$ 112.1	$ 70.5
Variable Interest Entity, Consolidated, Carrying Amount, Assets	223.4	175.8
New Ocean Capital Management Ltd
Variable Interest Entity [Line Items]
Non-controlling interest in consolidated subsidiaries	$ 1.0	$ 0.4