Recent Accounting Standards - Accounting impact (Details) - New Accounting Pronouncement, Early Adoption, Effect - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 30, 2017
New Accounting Pronouncement, Early Adoption [Line Items]
Decrease to the opening balance of retained earnings, Net of Tax			$ 6.1
Increase to the opening balance of retained earnings, net			$ 19.8
Decrease in income tax provision due to adoption of ASU No. 2016-9	$ 0.0	$ 12.8
Increase to weighted average diluted shares outstanding	49,176	80,657