Basis of Presentation and Summary of Significant Accounting Policies - Capital Additions and Related Depreciation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Estimated useful life	15 years
Interest costs capitalized	$ 7.6	$ 7.6	$ 9.6
Other direct and indirect costs capitalized	$ 36.8	$ 36.0	$ 32.9
Furniture and Fixtures
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	30 years