Property and Equipment, net - Interest Cost Capitalized and Depreciation and Amortization Expense for Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Property, Plant and Equipment [Abstract]
Interest cost capitalized	$ 3.0	$ 2.3	$ 6.0	$ 3.9
Depreciation and amortization expense for property and equipment	$ 24.5	$ 21.1	$ 48.6	$ 41.7