Equity Method Investments - Schedule of Equity Investments in Affiliates (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 174.2	$ 185.0
Mars
Schedule of Equity Method Investments [Line Items]
Equity method investments	81.4	84.0
Amount equity investment exceeds equity in net assets	10.4	11.1
Bengal
Schedule of Equity Method Investments [Line Items]
Equity method investments	76.7	75.6
Gain from contribution on equity investments	5.8	6.0
Poseidon
Schedule of Equity Method Investments [Line Items]
Equity method investments	16.1	25.4
Amount equity investment exceeds equity in net assets	$ 9.7	$ 10.3