Significant Accounting Policies and Practices - Schedule of New Accounting Pronouncements (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Assets
Prepaid expenses and other	$ 14.1	$ 17.2
Right-of-use assets	454.2	0.0
Favorable acquired lease contracts, net	0.0	17.6
Cost of contracts, net	4.4	9.2
Liabilities
Accrued rent	18.9	23.5
Short-term lease liabilities	117.6	0.0
Long-term lease liabilities	348.4	0.0
Unfavorable lease contracts, net	0.0	24.7
Other long-term liabilities	59.2	$ 58.6
Balances without Adoption of Topic 842
Assets
Prepaid expenses and other	14.5
Right-of-use assets	0.0
Favorable acquired lease contracts, net	15.8
Cost of contracts, net	8.5
Liabilities
Accrued rent	26.8
Short-term lease liabilities	0.0
Long-term lease liabilities	0.0
Unfavorable lease contracts, net	21.3
Other long-term liabilities	62.0
Accounting Standards Update 2016-02
Assets
Right-of-use assets	454.2
Favorable acquired lease contracts, net	(15.8)
Cost of contracts, net	(4.1)
Liabilities
Accrued rent	(7.9)
Short-term lease liabilities	117.6
Long-term lease liabilities	348.4
Unfavorable lease contracts, net	(21.3)
Other long-term liabilities	(2.8)
Accounting Standards Update 2016-02 | Impact of Adoption Increase/(Decrease)
Assets
Prepaid expenses and other	$ (0.4)