Consolidated Statements Of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net income (loss)	$ 45.3	$ 23.6
Adjustments to reconcile net income (loss) to income (loss) from continuing operations:
Depreciation	21.7	19.1
Amortization	21.1	19.7
Stock-based compensation expense	3.8	3.4
Retirement plans	2.2	3.7
Deferred income taxes	1.4	(2.9)
Other noncash income (expense)	(7.2)	(1.5)
Changes in assets and liabilities, net of acquisitions:
Receivables	17.4	2.9
Inventories	5.0	(23.3)
Other current assets and other noncurrent assets	0.7	(16.5)
Accounts payable	(25.6)	(25.5)
Walter Energy Accrual	(22.0)	38.4
Other current liabilities	6.0	(15.9)
Long-term liabilities	(6.4)	(10.4)
Net cash provided by (used in) operating activities, total	77.8	17.8
Investing activities:
Businesses acquisitions, net of cash received	0.0	(127.5)
Capital expenditures	(51.2)	(52.9)
Proceeds from sales of assets	0.3	0.0
Net cash provided by (used in) investing activities, total	(50.9)	(180.4)
Financing activities:
Dividends paid	(24.9)	(23.7)
Acquisition of joint venture partner's interest	5.2	0.0
Repayment of Krausz debt	0.0	(13.2)
Shares retained for employee taxes	(0.7)	(1.4)
Common stock issued	2.6	4.1
Other	0.6	0.3
Stock repurchased under buyback program	(5.0)	(10.0)
Net cash provided by (used in) financing activities, total	(32.6)	(43.9)
Effect of currency exchange rate changes on cash	(0.3)	0.1
Net change in cash and cash equivalents	(6.0)	(206.4)
Cash and cash equivalents at beginning of period	176.7	347.1
Cash and cash equivalents at end of period	$ 170.7	$ 140.7