Consolidated Statements Of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Net Cash Provided by (Used in) Operating Activities [Abstract]
Net Income (Loss) Attributable to Parent	$ 34.1	$ (10.1)
Adjustments to reconcile net income (loss) to income (loss) from continuing operations:
Depreciation	14.4	12.6
Amortization	13.9	12.9
Stock-based compensation expense	2.7	2.3
Retirement plans	1.4	3.2
Deferred income taxes	0.9	(3.8)
Other Noncash Income (Expense)	(2.2)	(1.7)
Changes in assets and liabilities, net of acquisitions:
Receivables	(8.2)	3.7
Inventories	(13.4)	(32.2)
Other current assets and other noncurrent assets	5.7	(10.1)
Accounts payable	(18.8)	(26.5)
Walter Energy Accrual	(22.0)	37.9
Other current liabilities	(9.9)	(11.9)
Long-term liabilities	(6.0)	(8.8)
Net Cash Provided by (Used in) Operating Activities, Total	(3.0)	(29.1)
Investing activities:
Payments to Acquire Businesses, Net of Cash Acquired	0.0	(127.5)
Capital expenditures	(37.3)	(30.5)
Proceeds from sales of assets	0.1	0.0
Net Cash Provided by (Used in) Investing Activities, Total	(37.2)	(158.0)
Financing activities:
Dividends paid	(16.6)	(15.8)
Payments to Noncontrolling Interests	5.2	0.0
Repayment of Krausz debt	0.0	(13.2)
Shares retained for employee taxes	(0.7)	(1.4)
Common stock issued	2.2	3.6
Other	0.5	0.1
Stock repurchased under buyback program	5.0	0.0
Net Cash Provided by (Used in) Financing Activities, Total	(24.8)	(26.7)
Effect of currency exchange rate changes on cash	(0.4)	1.0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect, Total	(65.4)	(212.8)
Cash and cash equivalents at beginning of period	176.7	347.1
Cash and cash equivalents at end of period	$ 111.3	$ 134.3