Property and Equipment, net - Interest Cost Capitalized and Depreciation and Amortization Expense for Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Interest cost capitalized	$ 1.8	$ 3.2	$ 7.8	$ 7.1
Depreciation and amortization expense for property and equipment	$ 27.3	$ 23.2	$ 75.9	$ 64.9