Fair Value Measurement - Assets and Liabilities Measured on Recurring Basis (Details) - Recurring basis - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Level 1
Assets
Assets measured at fair value	$ 0.0	$ 0.0
Level 2
Assets
Assets measured at fair value	0.0	0.1
Level 3
Assets
Assets measured at fair value	0.0	0.5
Interest rate swap | Level 1 | Prepaid expenses and other
Assets
Assets measured at fair value	0.0	0.0
Interest rate swap | Level 2 | Prepaid expenses and other
Assets
Assets measured at fair value	0.0	0.1
Interest rate swap | Level 3 | Prepaid expenses and other
Assets
Assets measured at fair value	0.0	0.0
Contingent consideration receivable | Level 1 | Prepaid expenses and other
Assets
Assets measured at fair value	0.0	0.0
Contingent consideration receivable | Level 2 | Prepaid expenses and other
Assets
Assets measured at fair value	0.0	0.0
Contingent consideration receivable | Level 3
Assets
Assets measured at fair value		0.5
Contingent consideration receivable | Level 3 | Prepaid expenses and other
Assets
Assets measured at fair value	$ 0.0	$ 0.5