Fair Value Measurement - Carrying Value and Estimated Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Fair Value Measurement
Long-term borrowings	$ 384.0	$ 386.7
Credit Facility, net of original discount on borrowings and deferred financing costs
Fair Value Measurement
Long-term borrowings	368.7	371.2
Credit Facility, net of original discount on borrowings and deferred financing costs | Carrying Amount
Fair Value Measurement
Long-term borrowings	368.7	371.2
Credit Facility, net of original discount on borrowings and deferred financing costs | Fair Value
Fair Value Measurement
Long-term borrowings	368.7	371.2
Other obligations
Fair Value Measurement
Long-term borrowings	15.3	15.5
Other obligations | Carrying Amount
Fair Value Measurement
Long-term borrowings	15.3	15.4
Other obligations | Fair Value
Fair Value Measurement
Long-term borrowings	$ 15.3	$ 15.4