Property and Equipment, net - Interest Cost Capitalized and Depreciation and Amortization Expense for Property and Equipment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Property, Plant and Equipment [Abstract]
Interest cost capitalized	$ 2.2	$ 3.0
Depreciation and amortization expense for property and equipment	$ 28.9	$ 24.1