Financial Instruments (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Derivative [Line Items]
Interest gain (loss) reclassified to earnings		$ 0.5	$ 0.0
Cap agreement effective 1/1/17-12/31/18
Derivative [Line Items]
Interest rate cap, cap rate	1.50%	1.50%
Notional amount	$ 1,400.0	$ 1,400.0
Interest rate cap, fair value	3.0	3.0		$ 5.0
Interest Rate Contract
Derivative [Line Items]
Unrealized loss on effective portion of interest rate cap agreements	2.0	1.0
Tax benefit	$ 1.0
Amount to be reclassified from AOCL to interest expense		1.0
Derivative
Derivative [Line Items]
Interest gain (loss) reclassified to earnings		$ 1.0	$ 1.0