Revenues - Performance Obligation Term (Details) - USD ($) $ in Millions	Dec. 31, 2018	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount		$ 488.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue from Contract with Customer [Abstract]
Revenue, remaining performance obligation, amount	$ 433.3
Revenue, remaining performance obligation, percent	88.60%
Revenue, remaining performance obligation, expected timing of satisfaction, period	12 months