Long-Term Debt - Interest Rate Swaps Additional Information (Details) - Interest Rate Swap - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2019	Apr. 30, 2018	Sep. 30, 2017	Sep. 29, 2017	Feb. 01, 2016
Derivative [Line Items]
Derivative, Notional Amount Per Derivative Instrument							$ 200.0
Derivative, Fixed Interest Rate				2.61%		1.69%
Derivative, Average Fixed Interest Rate							1.01%
Derivative, Gain (Loss) on Derivative, Net	$ 2.2	$ (6.7)
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion	0.7	5.4
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Month, Gross	2.7
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net	2.0
Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion	$ 1.6	$ 3.9
London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Derivative, Notional Amount Per Derivative Instrument				$ 250.0	$ 200.0	$ 200.0
Derivative, Basis Spread on Variable Rate	2.52%
Derivative, Fixed Interest Rate					2.08%
Subsequent Event
Derivative [Line Items]
Derivative, Fixed Interest Rate			2.65%
Subsequent Event | London Interbank Offered Rate (LIBOR) [Member]
Derivative [Line Items]
Derivative, Notional Amount Per Derivative Instrument			$ 300.0