Significant Accounting Policies - Cumulative Effect of Changes Due to Adoption of ASU 2014-09 (Details) - USD ($) $ in Millions	Dec. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Assets [Abstract]
Other current assets	$ 26.9	$ 22.1	$ 22.4
Property and equipment, net	912.5	782.8	757.5
Liabilities [Abstract]
Accrued expenses and other current liabilities		93.6	89.8
Other liabilities	39.4	37.2	15.7
SHAREHOLDERS' EQUITY
Retained earnings	$ 509.2	473.9	$ 474.2
Difference between Revenue Guidance in Effect before and after Topic 606 | Adoption of ASC 842
Assets [Abstract]
Other current assets		(0.3)
Property and equipment, net		25.3
Liabilities [Abstract]
Accrued expenses and other current liabilities		3.8
Other liabilities		21.5
SHAREHOLDERS' EQUITY
Retained earnings		$ (0.3)