Equity Method Investments - Summary of Income Statement Data for Equity Method Investments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015
Mars
Statements of Income
Total revenues	$ 44.9
Total operating expenses	17.6
Operating income	27.3
Net income	27.4
Bengal
Statements of Income
Total revenues	16.3
Total operating expenses	6.1
Operating income	10.2
Net income	$ 10.2