Fair Value Measurement - Schedule of Fair Values of Financial Assets and Liabilities (Details) - USD ($) $ in Millions		Dec. 31, 2019	Sep. 30, 2019
Assets:
Foreign currency exchange derivatives	[1]	$ 0.6	$ 0.8
Liabilities:
Foreign currency exchange derivatives	[1]	0.7	0.4
SERP Plan [Member]
Assets:
SERP plan assets	[2]	22.0	21.4
Level 1 | SERP Plan [Member]
Assets:
SERP plan assets	[2]	22.0	21.4
Level 2
Assets:
Foreign currency exchange derivatives	[1]	0.6	0.8
Liabilities:
Foreign currency exchange derivatives	[1]	$ 0.7	$ 0.4

[1] Based on observable market transactions of forward currency prices.

[2] Represents investments in a rabbi trust for the Company’s non-qualified supplemental executive retirement plan (SERP). The fair values of these investments are determined using a market approach. Investments include mutual funds for which quoted prices in active markets are available. The Company records changes in the fair value of investments in “Miscellaneous, net” in the Condensed Consolidated Statements of Income.