Recent Accounting Pronouncements - Cumulative Effect of Changes Due to Adoption of ASU 2014-09 (Details) - USD ($) $ in Millions	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
ASSETS
Other current assets	$ 37.8	$ 22.1	$ 22.4
Property and equipment, net	866.5	782.8	757.5
LIABILITIES
Accrued expense	78.0	93.6	89.8
Other liabilities	38.1	37.2	15.7
SHAREHOLDERS' EQUITY
Retained earnings	$ 457.8	473.9	$ 474.2
Accounting Standards Update 2016-02
ASSETS
Other current assets		(0.3)
Property and equipment, net		25.3
LIABILITIES
Accrued expense		3.8
Other liabilities		21.5
SHAREHOLDERS' EQUITY
Retained earnings		$ (0.3)