Development Projects Costs (Details) - USD ($) $ in Millions		9 Months Ended
	Feb. 08, 2018	Sep. 30, 2018	Dec. 31, 2017	Dec. 28, 2017	Sep. 30, 2017	Feb. 29, 2016
Development Costs [Line Items]
Capitalized project development costs		$ 19.5	$ 566.8
Project Development Costs Incurred Transferred to Property and Equipment	$ 653.2	630.1
Deposit assets					$ 20.0	$ 15.0
Deposit Asset, Percent of Minimum Capital Investment Expended for Deposit Return				85.00%
Construction Manager Costs [Member]
Development Costs [Line Items]
Capitalized project development costs		17.4	560.2
Architectural, Engineering, Construction Manager, and Subcontractor [Member]
Development Costs [Line Items]
Capitalized project development costs		$ 2.1	$ 6.6