Equity Method Investments - Summary of Balance Sheet and Income Statement Data for Equity Method Investments (Parenthetical) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015		Dec. 31, 2014
Poseidon
Schedule Of Equity Method Investments [Line Items]
Total revenues	$ 123.7
Total operating expenses	28.6
Operating income	95.1
Mars
Schedule Of Equity Method Investments [Line Items]
Total revenues	205.9	[1]	$ 160.5
Total operating expenses	85.7	[1]	73.0
Operating income	120.3	[1]	87.4
Bengal
Schedule Of Equity Method Investments [Line Items]
Total revenues	70.3	[1]	65.9
Total operating expenses	28.1	[1]	27.2
Operating income	$ 42.2	[1]	$ 38.7

[1] Interest in Poseidon was acquired by the Partnership on July 1, 2015. For 2015, Poseidon total revenue, total operating expenses and operating income (on a 100% basis) was $123.7 million, $28.6 million, and $95.1 million, respectively.