Mueller Water Products (MWA) 10-K 20 Nov 18 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2018	Nov. 12, 2018	Mar. 31, 2018	Sep. 30, 2017
Document Information [Line Items]
Document Fiscal Period Focus	FY
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Entity Well-known Seasoned Issuer	Yes
Entity Registrant Name	Mueller Water Products, Inc.
Entity Central Index Key	1,350,593
Current Fiscal Year End Date	--09-30
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Property, plant and equipment, net	$ 150,900,000			$ 122,300,000
Intangible Assets, Net (Including Goodwill)	$ 420,200,000			$ 439,300,000
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Amendment Flag	false
Entity Common Stock, Shares Outstanding		157,461,336
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Public Float			$ 1,702,200,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Assets:
Cash and cash equivalents	$ 347.1	$ 361.7
Receivables, net	164.3	145.3
Inventories	156.6	138.9
Other current assets	17.5	24.4
Total current assets	685.5	670.3
Property, plant and equipment, net	150.9	122.3
Intangible Assets, Net (Including Goodwill)	420.2	439.3
Other noncurrent assets	35.3	26.4
Total assets	1,291.9	1,258.3
Liabilities and equity:
Current portion of long-term debt	0.7	5.6
Accounts payable	90	82.5
Other current liabilities	76.4	53.5
Total current liabilities	167.1	141.6
Long-term debt, excluding current maturities	444.3	475
Deferred Tax Liabilities, Gross, Noncurrent	79.2	115.1
Other noncurrent liabilities	36.5	37.1
Total liabilities	727.1	768.8
Common Stock	1.6	1.6
Additional paid-in capital	1,444.5	1,494.2
Accumulated deficit	(850)	(955.6)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(32.8)	(51.8)
Stockholders' Equity Attributable to Parent	563.3	488.4
Equity Attributable to Noncontrolling Interest	1.5	1.1
Equity	564.8	489.5
Total liabilities and equity	$ 1,291.9	$ 1,258.3

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - shares	Sep. 30, 2018	Sep. 30, 2017
Statement of Financial Position [Abstract]
Series A common stock, shares authorized	600,000,000	600,000,000
Series A common stock, shares outstanding	157,332,121	158,590,383

Consolidated Statements Of Oper

Consolidated Statements Of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Revenues	$ 916	$ 826	$ 800.6
Cost of sales	626.1	558.1	531.7
Gross profit	289.9	267.9	268.9
Operating expenses:
Selling, general and administrative	166.7	155.4	149.5
Gain on sale of idle property	(9)	0	0
Other Cost and Expense, Operating	10.5	10.4	7.2
Total operating expenses	168.2	165.8	156.7
Operating income	121.7	102.1	112.2
Defined Benefit Plan, Net Periodic Benefit Cost other than Service Cost	1	1.4	19.3
Interest expense, net	20.9	22.2	23.6
Gain on settlement of interest rate swap contracts	(2.4)	0	0
Loss on early extinguishment of debt	6.5	0	0
Net Income Before Income Tax	95.7	78.5	69.3
Income tax expense (benefit)	(9.9)	24.2	24.2
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	105.6	54.3	45.1
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0	69	18.8
Net Income (Loss) Attributable to Parent	$ 105.6	$ 123.3	$ 63.9
Net loss per basic share:
Continuing operations, in dollars per share	$ 0.67	$ 0.34	$ 0.28
Discontinued operations, in dollars per share	0	0.43	0.12
Net income (loss) per basic share	0.67	0.77	0.40
Net loss per diluted share:
Income (Loss) from Discontinued Operations per share	0	0.42	0.11
Net income (loss) per diluted share	0.66	0.76	0.39
Continuing operations	$ 0.66	$ 0.34	$ 0.28
Weighted average shares outstanding:
Basic, in shares	158.2	160.1	161.3
Diluted, in shares	159.7	161.8	163.4
Dividends declared per share, in dollars per share	$ 0.190	$ 0.150	$ 0.100

Consolidated Statement of Compr

Consolidated Statement of Comprehensive Income Statement - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Net Income (Loss) Attributable to Parent	$ 105.6	$ 123.3	$ 63.9
Other comprehensive income (loss):
Minimum pension liability	(27.4)	(17.4)	(2.8)
Income tax effects	(6.9)	(6.7)	(1.1)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(3)	2.8	0.2
Amortization of interest expense on terminated swap contracts	2.4	4.9	(4.7)
Income tax effects	(0.9)	(1.9)	1.8
Other Comprehensive Income (Loss), Net of Tax	19	16.5	(1)
Comprehensive Income (Loss), Net of Tax, Attributable to Parent	$ 124.6	$ 139.8	$ 62.9

Consolidated Statement Of Stock

Consolidated Statement Of Stockholders' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated other comprehensive income (loss)	Noncontrolling Interest [Member]	Stock-based Compensation Related [Member]	Stock-based Compensation Related [Member]Common stock	Stock-based Compensation Related [Member]Additional paid-in capital	Stock-based Compensation Related [Member]Accumulated deficit	Stock-based Compensation Related [Member]Accumulated other comprehensive income (loss)	Stock-based Compensation Related [Member]Noncontrolling Interest [Member]
Balance at Sep. 30, 2015	$ 367.8	$ 1.6	$ 1,574.8	$ (1,142.8)	$ (67.3)	$ 1.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	63.6
Net Income (Loss) Attributable to Noncontrolling Interest						(0.3)
Net Income (Loss) Attributable to Parent	63.9	0	0	63.9	0
Dividends declared	(16.1)	0	(16.1)	0	0	0
Stock-based compensation	5.2	0	5.2	0	0	0
Shares retained for employee taxes							$ (3.3)	$ 0	$ (3.3)	$ 0	$ 0	$ 0
Stock issued under stock compensation plans	3.3	0	3.3	0	0	0
Other Comprehensive Income (Loss), Net of Tax	(1)	0	0	0	(1)	0
Balance at Sep. 30, 2016	419.5	1.6	1,563.9	(1,078.9)	(68.3)	1.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	123.2
Net Income (Loss) Attributable to Noncontrolling Interest						(0.1)
Net Income (Loss) Attributable to Parent	123.3	0	0	123.3	0
Dividends declared	(24)	0	(24)	0	0	0
Stock-based compensation	6.2	0	6.2	0	0	0
Shares retained for employee taxes							(2.7)	0	$ (2.7)	0	0	0
Stock issued under stock compensation plans	5.8	0	5.8	0	0	0
Stock repurchased under buyback program	(55)	0	(55)	0	0	0
Other Comprehensive Income (Loss), Net of Tax	16.5	0	0	0	16.5	0
Balance at Sep. 30, 2017	489.5	1.6	1,494.2	(955.6)	(51.8)	1.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	106
Net Income (Loss) Attributable to Noncontrolling Interest						0.4
Net Income (Loss) Attributable to Parent	105.6	0	0		0
Dividends declared	(30.1)	0	(30.1)	0	0	0
Stock-based compensation	5.2	0	5.2	0	0	0
Shares retained for employee taxes							$ (2.1)	$ 0		$ 0	$ 0	$ 0
Stock issued under stock compensation plans	7.3	0	7.3	0	0	0
Stock repurchased under buyback program	(30)	0	(30)	0	0	0
Other Comprehensive Income (Loss), Net of Tax	19	0	0	0	19	0
Balance at Sep. 30, 2018	$ 564.8	$ 1.6	$ 1,444.5	$ (850)	$ (32.8)	$ 1.5

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	$ 105.6	$ 54.3	$ 45.1
Net Income (Loss) Attributable to Parent	105.6	123.3	63.9
Adjustments to reconcile net income (loss) to income (loss) from continuing operations:
Income (loss) from discontinued operations, net of tax	0	(69)	(18.8)
Depreciation	20.9	19.8	18.3
Amortization	22.8	22.1	21.2
Pension plans	2.8	3.4	21
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2.8	3.4	21
Stock-based compensation expense	5.2	6	4.7
Deferred income taxes	(43.3)	(5.7)	(6.6)
Loss on early extinguishment of debt	6.5	0	0
Gain on sale of idle property	(9)	0	0
Other, net	3.4	1.1	3.8
Changes in assets and liabilities, net of acquisitions:
Receivables	(18.9)	(9.9)	(12.3)
Inventories	(18.4)	(1.9)	3.5
Other current assets and other noncurrent assets	(2)	(3.4)	(5.7)
Pension contributions	0	(35)	0
Accounts payable and other liabilities	57.5	8.6	21.5
Net cash provided by (used in) operating activities	133.1	59.4	114.5
Investing activities:
Capital expenditures	(55.7)	(40.6)	(31.5)
Acquisitions, net of cash acquired	0	(26.6)	0
Proceeds from sales of assets	7.8	0.9	0.3
Net cash provided by (used in) investing activities	(47.9)	(66.3)	(31.2)
Financing activities:
Repayment of debt	(486.3)	(4.9)	(5)
Issuance of debt	450	0	0
Dividends paid	(30.1)	(24)	(16.1)
Payments for Repurchase of Common Stock	(30)	(55)	0
Common stock issued	7.3	5.8	3.3
Payment of deferred financing fees	(6.9)	(1)	(1.2)
Shares retained for employee taxes	(2.1)	(2.7)	(3.3)
Other	(0.2)	0.4	(1.4)
Net cash used in financing activities	(98.3)	(81.4)	(23.7)
Effect of currency exchange rate changes on cash	(1.5)	1.2	(0.4)
Net Cash Provided by (Used in) Discontinued Operations [Abstract]
Operating activities	0	(43.3)	30.6
Investing activities	0	297.2	(7.9)
Net cash provided by (used in) discontinued operations	0	253.8	22.7
Financing activities	0	(0.1)	0
Net change in cash and cash equivalents	(14.6)	166.7	81.9
Cash and cash equivalents at beginning of period	361.7	195	113.1
Cash and cash equivalents at end of period	$ 347.1	$ 361.7	$ 195

Summary of Significant Accounti

Summary of Significant Accounting Policies All (Notes)	12 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Summary of Significant Accounting Policies Revenue Recognition -Revenue is recognized when delivery of products has occurred or services have been rendered and there is persuasive evidence of a sales arrangement, selling prices are fixed or determinable and collectibility is reasonably assured. Revenue is reported net of estimated discounts, returns and rebates as “net sales.” In May 2014, the Financial Accounting Standards Board (“FASB”) issued new guidance for the recognition of revenue and additional financial statement disclosures. We will adopt this guidance using the modified retrospective transition method beginning in the first quarter of fiscal 2019. During 2018, we completed our scoping and developed a project plan to classify our revenue streams, to evaluate revenue recognition practices for each stream against the new requirements, to consider changes to the terms of our sales contracts, and design and implement processes to quantify the effects of necessary changes. We have closely assessed the new guidance, including the interpretations by the FASB Transition Resource Group for Revenue Recognition, throughout 2018. We have completed the review of a sample of contracts with our customers that we believe are representative of our significant revenue streams. While we are substantially complete with the process of evaluating the impacts that will result from the new guidance, our assessment will be finalized during the first quarter of 2019. We expect that revenue for our primary revenue streams will be recognized at a point in time, which is similar to how revenue is recognized for these services under the previous guidance. We do not anticipate recording a material adjustment for the cumulative effect of adoption of the new guidance and we do not expect the new guidance to have a significant impact on our consolidated financial position, results of operations, equity or cash flows as of the adoption date beyond the required additional disclosures. We also have identified and have implemented and are implementing changes to our accounting policies and practices, business processes, systems and controls over the impacts of the new guidance on us, including the disclosure requirements and the collection of relevant data into the reporting process. Stock-based Compensation- Compensation expense for stock-based awards granted to employees and directors is based on the fair value at the grant dates for our stock-settled share awards and is based on the fair value at each reporting date for our cash-settled share awards. See Note 11. for more information regarding our stock-based compensation. Stock-based compensation expense is a component of selling, general and administrative expenses. Cash and Cash Equivalents- All highly liquid investments with remaining maturities of 90 days or less when purchased are classified as cash equivalents. Where there is no right of offset against cash balances, outstanding checks are included in accounts payable. Receivables- Receivables are amounts due from customers. To reduce credit risk, credit investigations are generally performed prior to accepting orders from new customers and, when necessary, letters of credit, bonds or other instruments are required to ensure payment. We present trade receivables net of an allowance for credit losses. Our consolidated statements of operations reflect the measurement of credit losses for newly recognized trade receivables, as well as the expected increases or decreases of expected credit losses that have taken place during the period. When we determine a specific trade receivable will not be collected, we charge off the uncollectible amount against the allowance. Our periodic evaluations of expected credit losses are based upon our judgments regarding prior collection experience, specific customer creditworthiness, other current conditions, and forecasts of current economic trends within the industries served that may affect the collectibility of the reported amounts. Significantly weaker than anticipated industry or economic conditions could impact customers’ ability to pay such that actual credit losses may be greater than the amounts provided for in this allowance. The following table summarizes information concerning our allowance for credit losses. 2018 2017 2016 (in millions) Balance at beginning of year $ 4.1 $ 4.5 $ 3.9 Provision charged to expense 0.5 0.3 0.6 Balances written off, net of recoveries (0.7 ) (0.8 ) — Other 0.1 0.1 — Balance at end of year $ 4.0 $ 4.1 $ 4.5 Inventories- Inventories are recorded at the lower of first-in, first-out method cost or estimated net realizable value. We evaluate our inventory in terms of excess and obsolete exposures. This evaluation includes such factors as anticipated usage, inventory turnover, inventory levels and ultimate product sales value. Inventory cost includes an overhead component that is affected by levels of production and actual costs incurred. We periodically evaluate the effects of production levels and costs capitalized as part of inventory. The following table summarizes information concerning our inventory valuation reserves. 2018 2017 2016 (in millions) Balance at beginning of year $ 4.4 $ 4.6 $ 4.4 Provision charged to expense 2.2 2.0 2.1 Inventory disposed (1.2 ) (2.1 ) (2.1 ) Other (0.3 ) (0.1 ) 0.2 Balance at end of year $ 5.1 $ 4.4 $ 4.6 Other Current Assets- Other current assets include maintenance supplies and tooling costs. Costs for perishable tools and maintenance items are expensed when put into service. Costs for more durable items are amortized over their estimated useful lives, ranging from 3 to 10 years. Property, Plant and Equipment- Property, plant and equipment is recorded at cost, less accumulated depreciation. Depreciation is recorded using the straight-line method over the estimated useful lives of the assets. Estimated useful lives are 10 to 20 years for land improvements, 10 to 40 years for buildings and 3 to 15 years for machinery and equipment. Leasehold improvements and capitalized leases are depreciated using the straight-line method over the lesser of the useful life of the asset or the remaining lease term. Gains and losses upon disposition are reflected in operating results in the period of disposition. Direct internal and external costs to implement computer systems and internal-use software are capitalized. Capitalized costs are depreciated over the estimated useful life of the system or software, generally 6 years, beginning when site installation or module development is complete and ready for use. Liabilities are recognized at fair value for asset retirement obligations related to plant and landfill closures in the period in which they are reasonably estimable and the carrying amounts of the related long-lived assets are correspondingly increased. Over time, the liabilities are accreted to their estimated future values. At September 30, 2018 and 2017 , asset retirement obligations were $4.1 million and $3.8 million , respectively. During 2016, FASB issued Accounting Standards Update 2016-02 Leases , which will require us to recognize lease assets and lease liabilities for those leases currently referred to as operating leases. This Update is effective for 2020 and requires the modified retrospective application and adoption of the requirement. We are currently evaluating the impact of this Update, which we do not believe will be material to our consolidated financial statements as a whole. Accounting for the Impairment of Long-Lived Assets- We test indefinite-lived intangible assets and goodwill for impairment annually (or more frequently if events or circumstances indicate possible impairment.) We perform our annual impairment testing at September 1. We amortize finite-lived intangible assets over their respective estimated useful lives and review for impairment if events or circumstances indicate possible impairment. Workers Compensation- Our exposure to workers compensation claims is generally limited to $1 million per incident. Liabilities, including those related to claims incurred but not reported, are recorded principally using annual valuations based on discounted future expected payments and using historical data combined with insurance industry data when historical data is limited. We are indemnified under an agreement with a predecessor to Tyco for all Mueller Co. and Anvil workers compensation liabilities related to incidents that occurred prior to August 16, 1999. See Note 17. We retained U.S. Pipe workers compensation liabilities related to incidents that occurred prior to the segment's April 1, 2012 sale date, but the purchaser agreed to reimburse us for up to $11.8 million in payments we make related to these liabilities. At September 30, 2018 , the remaining reimbursement receivable may be up to $4.5 million , which we have recorded on a discounted basis as $1.2 million in other current assets and $3.3 million in other noncurrent assets. On an undiscounted basis, workers compensation liabilities were $9.1 million and $10.7 million at September 30, 2018 and 2017 , respectively. On a discounted basis, workers compensation liabilities were $7.7 million and $9.1 million at September 30, 2018 and 2017 , respectively. We apply a risk-free discount rate, generally a U.S. Treasury bill rate, for each policy period. The rate used is one with a duration that corresponds to the weighted average expected payout period for each policy period. Once a discount rate is applied to a policy period, it remains the discount rate for that policy period until all claims are paid. Warranty Costs- We accrue for warranty expenses that can include costs of repair and/or replacement, including labor, materials, equipment, freight and reasonable overhead costs. We accrue for the estimated cost of product warranties at the time of sale if such costs are determined to be probable and reasonably estimable at that time. We monitor and analyze our warranty experience and costs periodically and may revise our warranty reserves as necessary. Critical factors in our reserve analyses include warranty terms, specific claim situations, general incurred and projected failure rates, the nature of product failures, product and labor costs, and general business conditions. As discussed in Note 17. we recognized $14.1 million and $9.8 million of Technologies' warranty expense during the years ended September 30, 2018 and 2017 , respectively, related to certain radios and other products sold in prior periods. Activity in accrued warranty, reported as part of both other current liabilities and other noncurrent liabilities, is presented below. 2018 2017 2016 (in millions) Balance at beginning of year $ 8.5 $ 2.0 $ 2.9 Warranty accruals 18.7 12.3 5.3 Warranty costs (7.2 ) (5.8 ) (6.2 ) Balance at end of year $ 20.0 $ 8.5 $ 2.0 Deferred Financing Costs- Costs of debt financing are charged to expense over the lives of the related financing agreements. Remaining costs and the future period over which they would be charged to expense are reassessed when amendments to the related financing agreements or prepayments occur. ABL Agreement deferred financing costs are included in other noncurrent assets and other deferred financing costs are offset against long-term debt in the accompanying consolidated balance sheets. Deferred financing costs of $7.4 million at September 30, 2018 are scheduled to amortize as follows: $0.8 million related to the ABL Agreement amortizes on a straight-line basis; $6.6 million related to the Senior Unsecured Notes amortizes using the effective-interest rate method. All such amortization will be over the remaining term of the respective debt. See Note 7. Derivative Instruments and Hedging Activities- We managed interest rate risk to some extent using derivative instruments. We had designated our interest rate swap contracts as cash flow hedges of interest payments. As a result, the changes in the fair value of these contracts prior to settlement were reported as a component of accumulated other comprehensive loss and were reclassified into earnings in the periods during which the hedged transactions affected earnings. We recorded a cash gain of $2.4 million in the quarter ended June 30, 2018 upon termination of the interest rate swaps. We also manage U.S. dollar - Canadian dollar exchange rate risk related to an intercompany loan with swap contracts that we have not designated as hedges. As a result, the changes in the fair value of these contracts are reported currently in earnings. Income Taxes- Deferred tax liabilities and deferred tax assets are recognized for the expected future tax consequences of events that have been included in the financial statements or tax returns. Such liabilities and assets are determined based on the differences between the financial statement basis and the tax basis of assets and liabilities, using tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is provided when, based upon the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We only record tax benefits for positions that management believes are more likely than not of being sustained under audit based solely on the technical merits of the associated tax position. The amount of tax benefit recognized for any position that meets the more likely than not threshold is the largest amount of the tax benefit that we believe is greater than 50% likely of being realized. On December 22, 2017, HR-1, commonly referred to as the Tax Cuts and Jobs Act (“Act”), was enacted, which made significant revisions to federal income tax laws, including lowering the corporate income tax rate to 21% from 35% effective January 1, 2018, overhauling the taxation of income earned outside the United States and eliminating or limiting certain deductions. The Act subjects us to current tax on global intangible low-taxed income (“GILTI”) earned by certain of our foreign subsidiaries. The Act states that we can make an accounting policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred. We have elected to recognize the tax on GILTI as a period expense in the period the tax is incurred. In September 2018, we adopted Accounting Standards Update 2018-02 Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which permits, but does not require, companies to reclassify from accumulated other comprehensive loss to retained earnings any “stranded tax effects” caused by the Act. We have elected to not make such a reclassification. Environmental Expenditures- We capitalize environmental expenditures that increase the life or efficiency of noncurrent assets or that reduce or prevent environmental contamination. We accrue for environmental expenses resulting from existing conditions that relate to past operations when the costs are probable and reasonably estimable. We are indemnified under an agreement with a predecessor to Tyco for certain environmental liabilities that existed at August 16, 1999. See Note 17. Research and Development- Research and development costs are expensed as incurred. Advertising- Advertising costs are expensed as incurred. Translation of Foreign Currency- Assets

Business Combination Business C

Business Combination Business Combination	12 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Business Combination Disclosure [Text Block]	Acquisition On February 15, 2017, we acquired Singer Valve, a manufacturer of automatic control valves, and its affiliates for aggregate cash consideration of $26.6 million , net of post-closing adjustments. Singer Valve had net sales of approximately $15 million in calendar 2016 and is included in Infrastructure. The allocation of consideration to the assets and liabilities of these companies, is presented below, in millions. Assets acquired, net of cash: Receivables $ 3.0 Inventories 5.8 Other current assets 0.2 Property, plant and equipment 1.0 Intangible assets 11.4 Goodwill 7.2 Liabilities assumed: Accounts payable 0.7 Other current liabilities 0.4 Current and long term debt 0.1 Deferred income tax liability 0.8 Consideration paid $ 26.6

Discontinued Operations, Assets

Discontinued Operations, Assets Held for Sale and Divestitures	12 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations, Assets Held for Sale and Divestitures	Divestiture On January 6, 2017 , we sold Anvil to affiliates of One Equity Partners for cash proceeds of $305.7 million and the agreement by the purchaser to reimburse us for expenditures to settle certain previously existing liabilities. The table below presents a summary of the sale of Anvil, in millions. Gross cash proceeds $ 305.7 Noncash proceeds 1.9 Total proceeds 307.6 Transaction expenses (8.3 ) Net proceeds 299.3 Assets and liabilities disposed (189.8 ) Gain on sale, pre-tax 109.5 Income tax (41.6 ) Gain on sale, net of tax $ 67.9 The table below presents a summary of the operating results for the Anvil discontinued operations. These operating results do not reflect what they would have been had Anvil not been classified as discontinued operations. 2017 2016 (in millions) Net sales $ 83.1 $ 338.3 Cost of sales 62.8 241.9 Gross profit 20.3 96.4 Operating expenses: Selling, general and administrative 17.2 67.6 Other charges 0.2 1.1 Total operating expenses 17.4 68.7 Operating income 2.9 27.7 Interest expense, net — — Income before income taxes 2.9 27.7 Income tax expense 1.8 8.9 1.1 18.8 Gain on sale, net of tax 67.9 — Income from discontinued operations $ 69.0 $ 18.8

Identifiable Intangible Assets

Identifiable Intangible Assets	12 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Identifiable Intangible Assets	Intangible Assets Direct internal and external costs to develop software licensed by Technologies' customers are capitalized. Capitalized costs are amortized over the 6 -year estimated useful life of the software, beginning when the software is complete and ready for its intended use. At September 30, 2018 , the remaining weighted-average amortization period for this software was 2.8 years. Amortization expense related to such software assets was $2.9 million , $2.4 million and $1.9 million for 2018 , 2017 and 2016 , respectively. Amortization expense for each of the next five years is scheduled to be $3.5 million in 2019 , $3.2 million in 2020 , $2.5 million in 2021 , $2.0 million in 2022 and $1.5 million in 2023 . At September 30, 2018 , the remaining weighted-average amortization period for the business combination-related finite-lived intangible assets was 6.8 years. Amortization expense related to these assets was $19.9 million , $19.7 million and $19.3 million for 2018 , 2017 and 2016 , respectively. Amortization expense for each of the next five years is scheduled to be $20.7 million in 2019 , $20.7 million in 2020 , $20.6 million in 2021 , $20.5 million in 2022 and $20.5 million in 2023 . Intangible assets are presented below. September 30, 2018 2017 (in millions) Capitalized internal-use software: Cost $ 27.6 $ 28.4 Accumulated amortization (14.2 ) (11.3 ) Net book value 13.4 17.1 Business combination-related: Cost: Finite-lived intangible assets: Technology 82.6 76.7 Customer relationships and other 358.8 359.2 Indefinite-lived intangible assets: Trade names and trademarks 266.6 266.8 Goodwill 12.1 12.9 720.1 715.6 Accumulated amortization: Technology (72.9 ) (72.2 ) Customer relationships and other (240.4 ) (221.2 ) (313.3 ) (293.4 ) Net book value 406.8 422.2 Total intangible assets net book value $ 420.2 $ 439.3

Income Taxes

Income Taxes	12 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The components of income before income taxes from continuing operations are presented below. 2018 2017 2016 (in millions) U.S. $ 97.3 $ 82.7 $ 69.7 Non-U.S. (1.6 ) (4.2 ) (0.4 ) Income before income taxes $ 95.7 $ 78.5 $ 69.3 On December 22, 2017, HR-1, commonly referred to as the Tax Cuts and Jobs Act (“Act”), was enacted, which made significant revisions to federal income tax laws, including lowering the corporate income tax rate to 21% from 35% effective January 1, 2018, overhauling the taxation of income earned outside the United States and eliminating or limiting certain deductions. Our deferred tax assets and liabilities are recorded at the enacted tax rates in effect when we expect to recognize the related tax expenses or benefits. The average of these rates varies slightly from year to year but historically has been approximately 39%. With the legislation changing rates taking place in the quarter ended December 31, 2017, we remeasured our deferred tax items at an average rate of approximately 25% and recorded an income tax benefit of $42.5 million . The Act also imposes a one-time transition tax on the undistributed, previously-untaxed, post-1986 foreign “earnings and profits” (as defined by the IRS) of certain U.S.-owned corporations. Determination of our transition tax liability requires us to calculate foreign earnings and profits going back to 1992 and then to assess our historical overall foreign loss position and the applicability of certain foreign tax credits. In March 2018, we recorded a provisional transition tax of $7.5 million for the one-time deemed repatriation tax on accumulated foreign earnings of our foreign subsidiaries and will finalize the transition tax in December 2018. We have not provided income taxes for unrepatriated foreign earnings that may be subject to withholding tax or any outside basis differences inherent in our foreign subsidiaries, as these amounts continue to be indefinitely reinvested in foreign operations. The Company has a foreign tax credit carryforward of $4.5 million that is not expected to be utilized prior to expiration. The components of income tax (benefit) expense from continuing operations are presented below. 2018 2017 2016 (in millions) Current: U.S. federal $ 25.7 $ 25.4 $ 28.9 U.S. state and local 7.1 4.0 2.0 Non-U.S. 0.6 0.5 (0.1 ) 33.4 29.9 30.8 Deferred: U.S. federal (42.6 ) (4.3 ) (9.8 ) U.S. state and local (1.0 ) (0.2 ) 3.4 Non-U.S. 0.3 (1.2 ) (0.2 ) (43.3 ) (5.7 ) (6.6 ) Income tax (benefit) expense $ (9.9 ) $ 24.2 $ 24.2 The reconciliation between income tax expense at the U.S. federal statutory income tax rate and reported income tax expense from continuing operations is presented below. 2018 2017 2016 (in millions) Expense at U.S. federal statutory income tax rates of 24.5%, 35% and 35%, respectively $ 23.4 $ 27.5 $ 24.3 Adjustments to reconcile to income tax expense: State income taxes, net of federal benefit 4.8 2.7 3.1 Domestic production activities deduction (2.4 ) (4.5 ) (3.0 ) Tax credits (1.7 ) (1.4 ) (2.0 ) Nondeductible expenses, other than compensation 0.5 0.6 0.7 Valuation allowances 0.5 0.4 — Foreign income taxes — 0.3 0.2 Nondeductible compensation 0.2 0.5 0.4 Excess tax benefits related to stock compensation (0.6 ) (2.1 ) (0.5 ) Federal tax rate change (42.5 ) (0.4 ) 0.4 Federal transition tax 7.5 — — Other 0.4 0.6 0.6 Income tax (benefit) expense $ (9.9 ) $ 24.2 $ 24.2 Deferred income tax balances are presented below. September 30, 2018 2017 (in millions) Deferred income tax assets: Inventory reserves $ 10.4 $ 12.0 Accrued expenses 13.3 14.9 Pension — 6.0 Stock-based compensation 3.3 6.2 State net operating losses 3.2 3.2 Federal credit carryovers 2.1 0.9 Other 1.0 2.7 33.3 45.9 Valuation allowance (1.9 ) (1.5 ) Total deferred income tax assets, net of valuation allowance 31.4 44.4 Deferred income tax liabilities: Intangible assets 95.7 151.2 Pension 2.3 — Other 11.4 7.2 Total deferred income tax liabilities 109.4 158.4 Net deferred income tax liabilities $ 78.0 $ 114.0 Balance sheet presentation: Deferred income taxes $ 79.2 $ 115.1 Less deferred tax assets included in other noncurrent assets 1.2 1.1 Net deferred income tax liabilities $ 78.0 $ 114.0 We reevaluate the need for a valuation allowance against our deferred tax assets each quarter, considering results to date, projections of taxable income, tax planning strategies and reversing taxable temporary differences. Our state net operating loss carryforwards, which expire between calendar years 2020 and 2033 , remain available to offset future taxable earnings. The following table summarizes information concerning our gross unrecognized tax benefits. 2018 2017 (in millions) Balance at beginning of year $ 3.0 $ 2.8 Increases related to prior year positions 0.1 0.1 Increases related to current year positions 0.3 0.2 Decreases due to lapse in statute of limitations (0.1 ) (0.1 ) Balance at end of year $ 3.3 $ 3.0 Substantially all unrecognized tax benefits would, if recognized, impact the effective tax rate. We recognize interest related to uncertain tax positions as interest expense and recognize any penalties incurred as a component of selling, general and administrative expenses. At September 30, 2018 and 2017 , we had $0.6 million and $0.7 million , respectively, of accrued interest expense related to unrecognized tax benefits. We expect to settle certain state income tax audits within the next 12 months and believe it is reasonably possible that these audit settlements will reduce the gross unrecognized tax benefits by $0.8 million . The federal income tax returns for Mueller Co. and Anvil are closed for years prior to 2005 and for Mueller Water Products, Inc. for 2007 and 2008. Our 2009 through 2012 returns are closed except to the extent net operating losses from those years have been utilized on subsequent years’ returns. We also remain liable for any taxes related to periods prior to the sale of U.S. Pipe in 2012 pursuant to the terms of the sale agreement with the purchaser of the segment. Certain tax years remain open for our predecessor company, U.S. Pipe, which was a subsidiary of Walter Energy in those years. See Note 17. Our state income tax returns are generally closed for years prior to 2014, except to the extent of our state net operating loss carryforwards. Our Canadian income tax returns are generally closed for years prior to 2011. We are currently under audit by several jurisdictions at various levels of completion. We do not

Borrowing Arrangements

Borrowing Arrangements	12 Months Ended
	Sep. 30, 2018
Long-term Debt and Capital Lease Obligations [Abstract]
Borrowing Arrangements	Borrowing Arrangements The components of our long-term debt are presented below. September 30, 2018 2017 (in millions) 5.5% Senior Notes $ 450.0 $ — ABL Agreement — — Term Loan — 484.8 Other 1.6 1.7 451.6 486.5 Deferred financing costs (6.6 ) (5.9 ) Less current portion (0.7 ) (5.6 ) Long-term debt $ 444.3 $ 475.0 The scheduled maturities of all borrowings outstanding at September 30, 2018 for each of the following years are. $0.7 million in 2019, $0.6 million in 2020, $0.3 million in 2021, $0.0 million in 2022 and $0.0 million in 2023. ABL Agreement . Our asset based lending agreement (“ABL Agreement”) consists of a revolving credit facility for up to $175 million of revolving credit borrowings, swing line loans and letters of credit. On July 19, 2018, we reduced our borrowing limit from $225 million to $175 million and wrote off a portion of the associated deferred financing costs, resulting in a loss on early extinguishment of debt of $0.3 million . The ABL Agreement also permits us to increase the size of the credit facility by an additional $150 million in certain circumstances. We may borrow up to $25 million through swing line loans and may have up to $60 million of letters of credit outstanding. Borrowings under the ABL Agreement bear interest at a floating rate equal to LIBOR plus a margin ranging from 125 to 150 basis points, or a base rate, as defined in the ABL Agreement, plus a margin ranging from 25 to 50 basis points. At September 30, 2018 the applicable rate was LIBOR plus 125 basis points. The ABL Agreement terminates on July 13, 2021 . We pay a commitment fee for any unused borrowing capacity under the ABL Agreement of 25 basis points per annum. Borrowings are not subject to financial maintenance covenants unless excess availability is less than the greater of $17.5 million and 10% of the Loan Cap as defined in the ABL Agreement. Excess availability based on September 30, 2018 data, as reduced by outstanding letters of credit and accrued fees and expenses of $18.3 million , was approximately $125 million . 5.5% Senior Unsecured Notes. On June 12, 2018 , we privately issued $450.0 million of 5.5% Senior Unsecured Notes (“Notes”), which mature in June 2026 and bear interest at 5.5% . We capitalized $6.6 million of financing costs, which are being amortized over the term of the Notes using the effective interest rate method. Proceeds from the Notes, along with other cash, were used to repay our Term Loan. Substantially all of our U.S. Subsidiaries guarantee the Notes, which are subordinate to borrowings under the ABL. Based on quoted market prices, the outstanding Notes had a fair value of $452.3 million at September 30, 2018 . An indenture securing the Notes (“Indenture”) contains customary covenants and events of default, including covenants that limit our ability to incur debt, pay dividends, and make investments. We believe we were compliant with these covenants at September 30, 2018 and expect to remain in compliance through September 30, 2019. We may redeem some or all of the Notes at any time or from time to time prior to June 15, 2021 at certain “make-whole” redemption prices (as set forth in the Indenture) and on or after June 15, 2021 at specified redemption prices (as set forth in the Indenture). Additionally, we may redeem up to 40% of the aggregate principal amount of the Notes at any time or from time to time prior to June 15, 2021 with the net proceeds of specified equity offerings at specified redemption prices (as set forth in the Indenture). Upon a change of control (as defined in the Indenture), we will be required to make an offer to purchase the Notes at a price equal to 101% of the outstanding principal amount of the Notes. Term Loan . We had a $500.0 million senior secured term loan (“Term Loan”), which accrued interest at a floating rate equal to LIBOR, subject to a floor of 0.75% , plus 250 basis points. The principal amount of the Term Loan was required to be repaid in quarterly installments, with any remaining principal due on November 25, 2021 . We repaid the Term Loan on June 15, 2018 with the proceeds from the issuance of the Notes and cash on hand. We wrote-off the associated deferred debt issuance costs and recorded a loss on the early extinguishment of debt of $6.2 million

Derivative Financial Instrument

Derivative Financial Instruments (Notes)	12 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Text Block]	Derivative Financial Instruments Prior to the June 15, 2018 retirement of our Term Loan, we were exposed to interest rate risk that we managed to some extent using derivative instruments. We terminated these instruments in conjunction with the retirement of the Term Loan. Under our interest rate swap contracts, we received interest calculated using 3-month LIBOR, subject to a floor of 0.750% , and paid fixed interest at 2.341% , on an aggregate notional amount of $150.0 million . These swap contracts effectively fixed the cash interest rate on $150.0 million of our borrowings under the Term Loan at 4.841% through September 30, 2021 . We had designated our interest rate swap contracts as cash flow hedges of our future interest payments and elected to apply the “shortcut” method of assessing hedge effectiveness. As a result, the gains and losses on the swap contracts had been reported as a component of other comprehensive loss and were reclassified into interest expense as the related interest payments were made. Upon termination of the interest rate swaps, we reclassified all associated amounts from accumulated other comprehensive loss to earnings, which resulted in a cash gain of $2.4 million in June 2018. In connection with the acquisition of Singer Valve discussed in Note 4. ,we loaned funds to one of our Canadian subsidiaries. Although this intercompany loan has no direct effect on our consolidated financial statements, it creates exposure to currency risk for the Canadian subsidiary. To reduce this exposure, we entered into a U.S. dollar-Canadian dollar swap contract with the Canadian subsidiary and an offsetting Canadian dollar-U.S. dollar swap with a domestic bank. We have not designated these swaps as hedges and the changes in their fair value are included in earnings, where they offset the currency gains and losses associated with the intercompany loan. The fair values of the swap contracts are presented below. September 30, 2018 2017 (in millions) Interest rate swap contracts, designated as cash flow hedges: Other current liabilities $ — $ 1.2 Other noncurrent liabilities — 1.3 $ — $ 2.5 Currency swap contracts, not designated as hedges: Other noncurrent liabilities $ 0.9 $ 1.3 The fair values and the classification of the fair values between current and noncurrent portions are based on calculated cash flows using publicly available interest rate forward rate yield curve information, but amounts due at the actual settlement dates are dependent on actual rates in effect at the settlement dates and may differ significantly from amounts shown above.

Retirement Plans

Retirement Plans	12 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
Pension and Other Postretirement Benefits Disclosure	Retirement Plans We have various pension plans (“Pension Plans”), which we fund in accordance with their requirements and, where applicable, in amounts sufficient to satisfy the minimum funding requirements of applicable laws. The Pension Plans provide benefits based on years of service and compensation or at stated amounts for each year of service. The measurement date for all Pension Plans was September 30. Our U.S. pension plan (“Plan”) comprised 98% of the Pension Plans’ obligations and 98% of the Pension Plans’ assets at September 30, 2018 . We did not contribute to the Plan in 2018 and do not anticipate contributing to the Plan in 2019. We plan to contribute $1.2 million to Canadian pension plans in 2019 . During 2018, with a recently negotiated labor contract, a group of our collectively bargained employees are no longer accruing benefits under a multi-employer pension plan. The affected employees are now participants in our defined contribution retirement plan with an employer match and one-time contribution vesting over the next three years of $0.4 million . We expect to withdraw from this multi-employer pension plan. During 2016, the Plan completed a pension obligation settlement program targeting vested, terminated participants not yet receiving benefits. Approximately 75% of eligible participants accepted settlement offers. The Plan distributed assets totaling $58.5 million . We incurred a non-cash pension settlement charge of $16.6 million as a result of the program, which had an immaterial impact on the Plan’s funded ratio. During March 2017, the Financial Accounting Standards Board issued Accounting Standards Update No. 2017-07 (“ASU 2017-07”). ASU 2017-07 required us to exclude from operating income the components of net periodic benefit cost other than service cost. We adopted ASU 2017-07 on October 1, 2017, and this adoption required reclassification of pension costs other than service in the 2017 and 2016 results, which has the effect of increasing operating income by those amounts. The components of net periodic benefit cost for our Pension Plans are presented below. 2018 2017 2016 (in millions) Service cost $ 1.8 $ 2.0 $ 1.7 Components of net periodic benefit cost excluded from operating income following adoption of ASU 2017-07: Interest cost 14.3 14.3 18.9 Expected return on plan assets (16.5 ) (16.9 ) (19.7 ) Amortization of actuarial net loss 3.2 4.0 3.4 Pension settlement — — 16.6 Other — — 0.1 Pension costs other than service 1.0 1.4 19.3 Net periodic benefit cost $ 2.8 $ 3.4 $ 21.0 Balance sheet information for Pension Plans with accumulated benefit obligations in excess of plan assets is presented below. September 30, 2018 2017 (in millions) Projected benefit obligations $ 6.2 $ 379.5 Accumulated benefit obligations 6.2 379.5 Fair value of plan assets 5.0 364.2 Balance sheet information for Pension Plans with accumulated benefit obligations less than plan assets is presented below. September 30, 2018 2017 (in millions) Projected benefit obligations $ 327.1 $ 1.0 Accumulated benefit obligations 327.1 1.0 Fair value of plan assets 338.5 2.1 Pension Plan activity in accumulated other comprehensive loss, before tax, in 2018 is presented below, in millions. Balance at beginning of year $ 93.4 Actuarial gain (24.2 ) Prior year actuarial loss amortization to net periodic cost (3.2 ) Balance at end of year $ 66.0 We amortize amounts in accumulated other comprehensive loss representing unrecognized prior year service cost and unrecognized loss related to the Pension Plans over the weighted average life expectancy of their inactive participants. Actuarial gains and losses are amortized using a corridor approach. The gain/loss corridor is equal to ten percent of the greater of the benefit obligation and the market-related value of assets. Gains and losses in excess of the corridor are generally amortized over the average remaining lifetime of the plan participants. We expect to amortize $2.0 million of unrecognized loss into net periodic benefit cost from accumulated other comprehensive loss in 2019 . The discount rates for determining the present value of pension obligations were selected using a “bond settlement” approach, which constructs a hypothetical bond portfolio that could be purchased such that the coupon payments and maturity values could be used to satisfy the projected benefit payments. The discount rate is the equivalent rate that results in the present value of the projected benefit payments equaling the market value of this bond portfolio. Only high quality (AA graded or higher), non-callable corporate bonds are included in this bond portfolio. We rely on the Pension Plans’ actuaries to assist in the development of the discount rate model. The expected returns on plan assets were determined with the assistance of the Pension Plans’ actuaries and investment consultants. Expected returns on plan assets were developed using forward looking returns over a time horizon of 10 to 15 years for major asset classes along with projected risk and historical correlations. A summary of key assumptions for our Pension Plans is below. Pension Plans 2018 2017 2016 Weighted average used to determine benefit obligations: Discount rate 4.37 % 3.88 % 3.68 % Weighted average used to determine net periodic cost: Discount rate 3.88 % 3.68 % 3.92 % Expected return on plan assets 4.68 % 5.16 % 5.50 % Amounts recognized for Pension Plans are presented below. Pension Plans 2018 2017 (in millions) Projected benefit obligations: Beginning of year $ 380.5 $ 403.1 Service cost 1.8 2.0 Interest cost 14.3 14.3 Actuarial gain (38.6 ) (14.5 ) Benefits paid (24.3 ) (24.8 ) Currency translation (0.3 ) 0.4 Decrease in obligation due to curtailment / settlement — — End of year $ 333.4 $ 380.5 Accumulated benefit obligations at end of year $ 333.4 $ 380.5 Plan assets: Beginning of year $ 366.3 $ 340.0 Actual return on plan assets 2.0 15.8 Employer contributions — 35.0 Currency translation (0.3 ) 0.4 Benefits paid (24.3 ) (24.8 ) Other (0.2 ) (0.1 ) End of year $ 343.5 $ 366.3 Accrued benefit cost at end of year: Funded (unfunded) status $ 10.1 $ (14.2 ) Recognized on balance sheet: Other noncurrent assets $ 11.2 $ 1.1 Other current liabilities (1.1 ) (1.1 ) Other noncurrent liabilities — (14.2 ) $ 10.1 $ (14.2 ) Recognized in accumulated other comprehensive loss, before tax: Prior year service cost $ — $ — Net actuarial loss 66.0 93.4 $ 66.0 $ 93.4 We maintain a single trust that holds the assets of the U.S. pension plan. For most of 2016, the strategic asset allocation was about 40% equity investments. Near the end of 2016, we directed our investment manager to adjust the asset allocation to about 30% equity investments. Near the end of 2017, we directed our investment manager to adjust the asset allocation to about 20% equity investments. This trust’s strategic asset allocations, tactical range at September 30, 2018 and actual asset allocations are presented below. Strategic asset allocation Actual asset allocations at September 30, Tactical range 2018 2017 2016 Fixed income investments 80 % 75 80 % 77 % 78 % 69 % Equity investments 20 15 - 20 % 21 21 29 Cash — 0 - 5 % 2 1 2 100 % 100 % 100 % 100 % Assets of the Pension Plans are allocated to various investments to attain diversification and reasonable risk-adjusted returns while also managing the exposure to asset and liability volatility. These ranges are targets and deviations may occur from time to time due to market fluctuations. Portfolio assets are typically rebalanced to the allocation targets at least annually. The assets of the Pension Plans are primarily invested in investment trusts valued at net asset value, which in turn hold fixed income and equity investments. The valuation methodologies used to measure the assets of the Pension Plans at fair value are: • Fixed income fund investments held by the investment trusts are valued using the closing price reported in the active market in which the investment is traded or based on yields currently available on comparable securities of issuers with similar credit ratings; • Equity investments held by the investment trusts are valued using the closing price reported on the active market when reliable market quotations are readily available. When market quotations are not readily available, these assets are valued by a method the trustees believe accurately reflects fair value; and • Mutual funds are valued at the closing price reported on the active market. The assets of the Pension Plans by level within the fair value hierarchy are presented below. September 30, 2018 Level 1 Level 2 Total (in millions) Fixed income $ — $ 264.1 $ 264.1 Equity: Large cap stocks: Large cap index funds — 30.5 30.5 Mid cap stocks: Mid cap index funds — 10.1 10.1 Small cap stocks: Small cap growth funds — 10.0 10.0 International stocks: Mutual funds 11.8 — 11.8 International funds — 10.3 10.3 Total equity 11.8 60.9 72.7 Cash and cash equivalents 6.6 — 6.6 $ 18.4 $ 325.0 $ 343.4 September 30, 2017 Level 1 Level 2 Total (in millions) Fixed income $ — $ 284.4 $ 284.4 Equity: Large cap stocks: Large cap growth funds $ — $ 32.6 $ 32.6 Mid cap stocks: Mid cap index funds — 10.9 10.9 Small cap stocks: Small cap growth funds — 11.3 11.3 International stocks: Mutual funds 15.4 — 15.4 International funds — 7.4 7.4 Total equity 15.4 62.2 77.6 Cash and cash equivalents 4.3 — 4.3 $ 19.7 $ 346.6 $ 366.3 Our estimated future pension benefit payments are presented below in millions. 2019 $ 31.2 2020 25.0 2021 24.8 2022 24.5 2023 24.2 2024-2028 113.6 Defined Contribution Retirement Plans- Certain of our employees participate in defined contribution 401(k) plans or similar non-U.S plans. We make matching contributions as a function of employee contributions. Matching contributions were $4.7 million , $4.1 million and $4.0 million during 2018 , 2017 and 2016

Capital Stock

Capital Stock	12 Months Ended
	Sep. 30, 2018
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Stockholders' Equity Note Disclosure	Capital Stock Common stock share activity is presented below. Shares outstanding at September 30, 2015 160,497,841 Vesting of restricted stock units, net of shares withheld for taxes 370,138 Exercise of stock options 270,599 Exercise of employee stock purchase plan instruments 218,475 Settlement of performance-based restricted stock units, net of shares withheld for taxes 335,998 Shares outstanding at September 30, 2016 161,693,051 Vesting of restricted stock units, net of shares withheld for taxes 262,488 Exercise of stock options 905,834 Exercise of employee stock purchase plan instruments 150,174 Settlement of performance-based restricted stock units, net of shares withheld for taxes 160,063 Stock repurchased under buyback program (4,581,227 ) Shares outstanding at September 30, 2017 158,590,383 Vesting of restricted stock units, net of shares withheld for taxes 232,875 Exercise of stock options 851,628 Exercise of employee stock purchase plan instruments 150,669 Settlement of performance-based restricted stock units, net of shares withheld for taxes 86,516 Stock repurchased under buyback program (2,573,475 ) Other (6,475 ) Shares outstanding at September 30, 2018 157,332,121

Stock-based Compensation Plans

Stock-based Compensation Plans	12 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Stock-based Compensation Plans The effect of stock-based compensation on our statements of operations, including discontinued operations, is presented below. 2018 2017 2016 (in millions, except per share data) Decrease in operating income $ 6.4 $ 8.6 $ 9.1 Decrease in net income 4.0 4.8 5.8 Decrease in earnings per basic share 0.03 0.03 0.04 Decrease in earnings per diluted share 0.03 0.03 0.04 We excluded 214,435 , 238,826 and 867,065 instruments from the calculation of diluted earnings per share for 2018 , 2017 and 2016 , respectively, because the effect of including them would have been antidilutive. At September 30, 2018 , there was approximately $5.1 million of unrecognized compensation expense related to stock-based awards not yet vested. We expect to recognize this expense over a weighted average life of approximately 1.37 years. The Mueller Water Products, Inc. 2006 Stock Incentive Plan (“2006 Plan”) authorizes an aggregate of 20,500,000 shares of common stock that may be granted through the issuance of stock-based awards. Any awards canceled are available for reissuance. Generally, all of our employees and members of our board of directors are eligible to participate in the 2006 Plan. At September 30, 2018 , 7,410,033 shares of common stock were available for future grants of awards under the 2006 Plan. This total assumes that the maximum number of shares will be earned for awards for which the final number of shares to be earned has not yet been determined. An award granted under the 2006 Plan vests at such times and in such installments as set by the Compensation and Human Resources Committee of the board of directors, but no award will be exercisable after the 10 -year anniversary of the date on which it is granted. Management expects some instruments will be forfeited prior to vesting. Grants to members of our board of the directors are expected to vest fully. Based on historical forfeitures, we expect grants to others to be forfeited at an annual rate of 2% . Restricted Stock Units. Depending on the specific terms of each award, restricted stock units generally vest ratably over the life of the award, usually 3 years, on each anniversary date of the original grant. Compensation expense for restricted stock units is recognized between the grant date and the vesting date (or the date on which a participant becomes Retirement-eligible, if sooner) on a straight-line basis for each tranche of each award. Fair values of restricted stock units are determined using the closing price of our common stock on the respective dates of grant. Restricted stock unit activity under the 2006 Plan is summarized below. Restricted stock units Weighted average grant date fair value per unit Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 872,790 $ 8.45 0.8 Granted 360,255 9.33 Vested (510,535 ) 7.94 $ 4.7 Cancelled (59,062 ) 8.23 Outstanding at September 30, 2016 663,448 9.34 1.0 Granted 343,860 13.05 Vested (359,797 ) 9.34 4.7 Cancelled (21,681 ) 13.26 Outstanding at September 30, 2017 625,830 11.23 0.9 Granted 276,658 12.20 Vested (342,038 ) 10.84 4.2 Cancelled (78,888 ) 11.41 Outstanding at September 30, 2018 481,562 12.14 1.0 Performance Shares. Performance-based restricted stock units (“PRSUs”) represent a target number of units that may be paid out at the end of a multi-year award cycle consisting of annual performance periods coinciding with our fiscal years. As determined at the date of award, PRSUs may settle in cash-value equivalent of, or directly in, shares of our common stock. Settlement will range from zero to two times the number of PRSUs granted, depending on our financial performance against predetermined targets. The Compensation and Human Resources Committee of our board of directors (“Committee”) establishes performance goals within 90 days of the beginning of each performance period, with such date referred to as the “grant date”. At the end of each annual performance period, the Committee confirms performance against the applicable performance targets. PRSUs do not convey voting rights or earn dividends. PRSUs vest on the last day of an award cycle, unless vested sooner due to a “Change of Control” of the Company, or the death, disability or Retirement of a participant. We recognize compensation expense for stock-settled PRSUs starting on the first day of the applicable performance period and ending on the respective vesting dates. We base the recognized compensation expense upon the number of units awarded for each performance period, the closing price of our common stock on the grant date and the estimated performance factor. In 2018 and 2017, 146,061 shares and 263,410 shares, respectively, vested related to PRSUs. Stock-settled PRSUs activity under the 2006 Plan is summarized below. Award date Settlement year Performance period Grant date per unit fair value Units awarded Units forfeited Net units Performance factor Shares earned December 3, 2013 2017 2014 $ 8.52 90,841 (4,401 ) 86,440 2.000 172,880 2015 $ 9.78 90,841 (4,401 ) 86,440 0.000 — 2016 $ 9.38 90,849 (7,402 ) 83,447 1.021 85,199 December 2, 2014 2018 2015 $ 9.78 80,233 (3,835 ) 76,398 0.000 — 2016 $ 9.38 80,229 (6,447 ) 73,782 1.021 75,327 2017 $ 13.26 80,229 (11,673 ) 68,556 1.000 68,556 December 1, 2015 2019 2016 $ 9.38 77,823 (3,998 ) 73,825 1.021 75,375 2017 $ 13.26 77,824 (3,997 ) 73,827 1.000 73,827 2018 $ 12.50 77,824 (61,841 ) 15,983 1.357 21,689 November 29, 2016 2020 2017 $ 13.26 59,285 (5,279 ) 54,006 1.000 54,006 2018 $ 12.50 59,286 (39,910 ) 19,376 1.357 26,294 2019 59,290 (39,909 ) 19,381 January 23, 2017 2020 2017 $ 13.15 19,012 — 19,012 1.000 19,012 2018 $ 12.50 19,011 — 19,011 1.357 25,798 2019 19,011 — 19,011 November 28, 2017 2021 2018 $ 12.50 57,092 — 57,092 1.357 77,474 2019 57,092 — 57,092 2020 57,104 — 57,104 Stock Options. Stock options generally vest ratably over 3 years on each anniversary date of the original grant. Stock options granted since November 2007 also vest upon the Retirement of a participant. Compensation expense for stock options is recognized between the grant date and the vesting date (or the date on which a participant becomes Retirement-eligible, if sooner) on a straight-line basis for each tranche of each award. No stock options were granted since 2015. Stock option activity under the 2006 Plan is summarized below. Options Weighted average exercise price per option Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 3,992,666 $ 6.54 4.2 $ 9.3 Exercised (270,599 ) 6.83 0.8 Cancelled (167,759 ) 17.82 Outstanding at September 30, 2016 3,554,308 5.99 3.4 23.8 Exercised (905,834 ) 4.71 7.3 Cancelled (207,820 ) 14.72 Outstanding at September 30, 2017 2,440,654 5.72 2.5 17.3 Exercised (851,628 ) 7.00 3.8 Cancelled — — Outstanding at September 30, 2018 1,589,026 $ 5.03 1.9 $ 10.3 Exercisable at September 30, 2018 1,589,026 $ 5.03 1.9 $ 10.3 Stock option exercise prices are equal to the closing price of our common stock on the relevant grant date. The ranges of exercise prices for stock options outstanding at September 30, 2018 are summarized below. Exercise price Options Weighted average exercise price Weighted average remaining contractual term (years) Exercisable options Weighted average exercise price $ 0.00 - $ 4.99 555,319 $ 3.32 2.4 555,319 $ 3.32 $ 5.00 - $ 9.99 1,033,707 5.95 1.6 1,033,707 5.95 1,589,026 $ 5.03 1.9 1,589,026 $ 5.03 Employee Stock Purchase Plan. The Mueller Water Products, Inc. 2006 Employee Stock Purchase Plan (“ESPP”) authorizes the sale of up to 5,800,000 shares of our common stock to employees. Generally, all full-time, active employees are eligible to participate in the ESPP, subject to certain restrictions. Employee purchases are funded through payroll deductions, and any excess payroll withholdings are returned to the employee. The price for shares purchased under the ESPP is 85% of the lower of the closing price on the first day or the last day of the offering period. At September 30, 2018 , 2,750,935 shares were available for issuance under the ESPP. Phantom Plan. Under the Mueller Water Products, Inc. Phantom Plan adopted in 2012 (“Phantom Plan”), we have awarded “phantom units” to certain non-officer employees. A phantom unit settles in cash equal to the price of one share of our common stock on the vesting date. Phantom units vest ratably over 3 years on each anniversary date of the original grant. We recognize compensation expense for phantom units on a straight-line basis for each tranche of each award based on the closing price of our common stock at each balance sheet date. The outstanding phantom units had a fair value of $11.51 per unit at September 30, 2018 and our accrued liability for such units was $3.0 million . Phantom Plan activity is summarized below. Phantom Plan units Weighted average grant date fair value per unit Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 558,878 $ 6.22 0.8 Granted 302,875 9.84 Vested (270,822 ) $ 3.1 Cancelled (56,905 ) 9.28 Outstanding at September 30, 2016 534,026 9.60 0.9 Granted 199,260 13.22 Vested (278,000 ) 3.7 Cancelled (103,279 ) 10.87 Outstanding at September 30, 2017 352,007 11.36 0.9 Granted 163,199 12.40 Vested (170,675 ) 2.1 Cancelled (81,758 ) 12.10 Outstanding at September 30, 2018 262,773 12.12 0.6

Supplemental Balance Sheet Info

Supplemental Balance Sheet Information	12 Months Ended
	Sep. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Supplemental Balance Sheet Information	Supplemental Balance Sheet Information Selected supplemental balance sheet information is presented below. September 30, 2018 2017 (in millions) Inventories: Purchased components and raw material $ 81.6 $ 67.7 Work in process 37.8 35.6 Finished goods 37.2 35.6 $ 156.6 $ 138.9 Other current assets: Maintenance and repair tooling $ 3.5 $ 3.3 Income taxes 1.6 10.9 Other 12.4 10.2 $ 17.5 $ 24.4 Property, plant and equipment: Land $ 5.4 $ 5.6 Buildings 55.9 53.4 Machinery and equipment 311.4 266.7 Construction in progress 22.2 24.7 $ 394.9 $ 350.4 Accumulated depreciation (244.0 ) (228.1 ) $ 150.9 $ 122.3 Other current liabilities: Compensation and benefits $ 31.7 $ 26.9 Customer rebates 9.7 6.5 Taxes other than income taxes 3.3 3.2 Warranty 6.0 3.5 Environmental 1.2 1.3 Income taxes 7.6 0.9 Interest 8.0 0.6 Restructuring 0.9 3.3 Other 8.0 7.3 $ 76.4 $ 53.5

Supplemental Statement of Opera

Supplemental Statement of Operations Information	12 Months Ended
	Sep. 30, 2018
Supplemental Income Statement Elements [Abstract]
Statement of Operations, Supplemental Disclosures [Text Block]	Supplemental Statement of Operations Information On September 7, 2017, we announced a strategic reorganization plan designed to accelerate our product innovation and revenue growth. We have adopted a matrix management structure, where business teams have line and cross-functional responsibility for managing distinct product portfolios. Engineering, operations, sales and marketing and other functions were centralized to better align with business needs and generate greater efficiencies. We recorded $4.6 million in other charges primarily for severance related to this strategic reorganization plan in 2018, of which $0.9 million was accrued at September 30, 2018. This plan is substantially complete. During the quarter ended June 30, 2016, we initiated certain demolition and related activities for our Statesboro, Georgia property, some of the costs of which are indemnified by Tyco as explained in Note 17. Corporate recorded a receivable from Tyco for our estimated recovery under the indemnification and a net charge of $4.1 million under the caption other charges in 2016. Selected supplemental statement of operations information is presented below. 2018 2017 2016 (in millions) Included in selling, general and administrative expenses: Research and development $ 11.6 $ 12.1 $ 9.9 Advertising $ 7.1 $ 5.2 $ 4.0 Interest expense, net: Term Loan $ 14.4 $ 19.1 $ 20.5 Deferred financing costs amortization 1.6 1.8 1.9 ABL Agreement 0.6 0.8 1.1 Interest rate swap contracts 0.6 1.9 — 5.5% Senior Notes 7.5 — — Other interest expense 0.6 0.6 0.5 25.3 24.2 24.0 Interest income (4.4 ) (2.0 ) (0.4 ) $ 20.9 $ 22.2 $ 23.6

Accumulated Other Comprehensive

Accumulated Other Comprehensive Loss	12 Months Ended
	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Comprehensive Income (Loss) Note [Text Block]	Accumulated Other Comprehensive Loss Accumulated other comprehensive loss is presented below. Foreign currency translation Pension liability, net of tax Derivative instruments, net of tax Total (in millions) Balance at September 30, 2017 $ (3.3 ) $ (47.0 ) $ (1.5 ) $ (51.8 ) Other comprehensive income before reclassifications (3.0 ) 17.9 — 14.9 Amounts reclassified out of accumulated other comprehensive loss — 2.6 1.5 4.1 Other comprehensive income (3.0 ) 20.5 1.5 19.0 Balance at September 30, 2018 $ (6.3 ) $ (26.5 ) $ — $ (32.8 )

Supplemental Cash Flow Informat

Supplemental Cash Flow Information	12 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Information [Abstract]
Cash Flow, Supplemental Disclosures [Text Block]	Supplemental Cash Flow Information Supplemental cash flow information is presented below. September 30, 2018 2017 2016 (in millions) Cash paid, net: Interest $ 8.9 $ 19.5 $ 21.1 Income taxes $ 10.7 $ 31.9 $ 27.1

Segment Information

Segment Information	12 Months Ended
	Sep. 30, 2017
Segment Reporting [Abstract]
Segment Reporting Disclosure [Text Block]	Segment Information Our operations consist of two business segments: Infrastructure (previously referred to as “Mueller Co.”) and Technologies (previously referred to as “Mueller Technologies”). These segments are organized primarily based on products sold and customers served and are consistent with how the segments are managed, how resources are allocated and how information is used by the chief operating decision maker. Infrastructure manufactures valves for water and gas systems including butterfly, iron gate, tapping, check, knife, plug, automatic control and ball valves and dry-barrel and wet-barrel fire hydrants. Technologies offers metering, leak detection, pipe condition assessment and other products and services for the water infrastructure industry. Segment results are not reflective of their results on a stand-alone basis. Intersegment sales and transfers are made at selling prices generally intended to cover costs. Infrastructure personnel provide certain administrative services, including management of accounts payable and accounts receivable, without any allocation of cost to Technologies. We do not believe the costs of such administrative services are material to the segments’ results. The determination of segment results excludes certain corporate expenses designated as Corporate because they are not directly attributable to segment operations. Interest expense, loss on early extinguishment of debt and income taxes are not allocated to the segments. Corporate expenses include those costs incurred by our corporate function, such as accounting, treasury, risk management, human resources, legal, tax and other administrative functions and also costs associated with assets and liabilities retained following the sales of U.S. Pipe and Anvil. Corporate assets principally consist of our cash, Anvil assets held for sale at September 30, 2017 and certain real property previously owned by U.S. Pipe and Anvil. Business segment assets consist primarily of receivables, inventories, property, plant and equipment, intangible assets and other noncurrent assets. Geographical area information is presented below. United States Canada Other Total (in millions) Net sales: 2018 $ 812.2 $ 71.7 $ 32.1 $ 916.0 2017 732.0 62.3 31.7 826.0 2016 716.5 57.1 27.0 800.6 Property, plant and equipment, net: September 30, 2018 $ 144.8 $ 3.4 $ 2.7 $ 150.9 September 30, 2017 116.1 3.0 3.2 122.3 Approximately 54% of our 2018 gross sales were to our 10 largest customers, and approximately 34% of our 2018 gross sales were to our two largest customers, Ferguson Enterprises, Inc. (“Ferguson Enterprises”) and Core & Main LP. (“Core & Main)”). Sales to Ferguson Enterprises comprised approximately 19% , 18% and 17% of our total gross sales during 2018 , 2017 and 2016 , respectively. In 2018 , Ferguson Enterprises accounted for approximately 18% and 28% of gross sales for Infrastructure and Technologies, respectively. Receivables from Ferguson Enterprises totaled $29.7 million and $20.0 million at September 30, 2018 and 2017 , respectively. Sales to Core & Main comprised approximately 15% , 16% and 16% of our total gross sales during 2018 , 2017 , and 2016 , respectively. In 2018 , Core & Main accounted for approximately 17% of gross sales for Infrastructure. Receivables from Core & Main totaled $31.7 million and $27.3 million at September 30, 2018 and 2017 , respectively. Summarized financial information for our segments is presented below. Infrastructure Technologies Corporate Total (in millions) Net sales, excluding intercompany: 2018 $ 818.8 $ 97.2 $ — $ 916.0 2017 739.9 86.1 — 826.0 2016 715.7 84.9 — 800.6 Intercompany sales: 2018 $ — $ — $ — $ — 2017 — — — — 2016 5.8 — — 5.8 Operating income (loss): 2018 $ 180.1 $ (24.4 ) $ (34.0 ) $ 121.7 2017 163.8 (20.3 ) (41.4 ) 102.1 2016 162.5 (11.1 ) (39.2 ) 112.2 Depreciation and amortization: 2018 $ 37.4 $ 6.1 $ 0.2 $ 43.7 2017 36.3 5.2 0.4 41.9 2016 34.2 4.8 0.5 39.5 Total pension settlement and other charges: 2018 $ 0.1 $ 0.1 $ 10.3 $ 10.5 2017 2.7 0.7 7.0 10.4 2016 1.0 0.9 5.8 7.7 Capital expenditures: 2018 $ 47.3 $ 8.3 $ 0.1 $ 55.7 2017 28.5 11.4 0.7 40.6 2016 24.3 7.0 0.2 31.5 Total assets: September 30, 2018 $ 843.9 $ 87.1 $ 360.9 $ 1,291.9 September 30, 2017 792.6 88.4 377.3 1,258.3 Intangible assets, net: September 30, 2018 $ 396.9 $ 23.3 $ — $ 420.2 September 30, 2017 417.2 22.1 — 439.3

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	Commitments and Contingencies We are involved in various legal proceedings that have arisen in the normal course of operations, including the proceedings summarized below. The effect of the outcome of these matters on our financial statements cannot be predicted with certainty as any such effect depends on the amount and timing of the resolution of such matters. Other than the litigation described below, we do not believe that any of our outstanding litigation would have a material adverse effect on our business or prospects. Environmental. We are subject to a wide variety of laws and regulations concerning the protection of the environment, both with respect to the operations at many of our properties and with respect to remediating environmental conditions that may exist at our own or other properties. We accrue for environmental expenses resulting from existing conditions that relate to past operations when the costs are probable and reasonably estimable. In the acquisition agreement pursuant to which a predecessor to Tyco sold our businesses to a previous owner in August 1999, Tyco agreed to indemnify us and our affiliates, among other things, for all “Excluded Liabilities.” Excluded Liabilities include, among other things, substantially all liabilities relating to the time prior to August 1999, including environmental liabilities. The indemnity survives indefinitely. Tyco’s indemnity does not cover liabilities to the extent caused by us or the operation of our businesses after August 1999, nor does it cover liabilities arising with respect to businesses or sites acquired after August 1999. Since 2007, Tyco has engaged in multiple corporate restructurings, split-offs and divestitures. While none of these transactions directly affects the indemnification obligations of the Tyco indemnitors under the 1999 acquisition agreement, the result of such transactions is that the assets of, and control over, such Tyco indemnitors has changed. Should any of these Tyco indemnitors become financially unable or fail to comply with the terms of the indemnity, we may be responsible for such obligations or liabilities. On July 13, 2010, Rohcan Investments Limited, the former owner of property leased by Mueller Canada Ltd. and located in Milton, Ontario, filed suit against Mueller Canada Ltd. and its directors seeking C$10.0 million in damages arising from the defendants’ alleged environmental contamination of the property and breach of lease. Mueller Canada Ltd. leased the property from 1988 through 2008. We are pursuing indemnification from a former owner for certain potential liabilities that are alleged in this lawsuit, and we have accrued for other liabilities not covered by indemnification. On December 7, 2011, the Court denied the plaintiff’s motion for summary judgment. The purchaser of U.S. Pipe has been identified as a “potentially responsible party” (“PRP”) under the Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA”) in connection with a former manufacturing facility operated by U.S. Pipe that was in the vicinity of a proposed Superfund site located in North Birmingham, Alabama. Under the terms of the acquisition agreement relating to our sale of U.S. Pipe, we agreed to indemnify the purchaser for certain environmental liabilities, including those arising out of the former manufacturing site in North Birmingham. Accordingly, the purchaser tendered the matter to us for indemnification, which we accepted. Ultimate liability for the site will depend on many factors that have not yet been determined, including the determination of EPA’s remediation costs, the number and financial viability of the other PRPs (there are four other PRPs currently) and the determination of the final allocation of the costs among the PRPs. Accordingly, because the amount of such costs cannot be reasonably estimated at this time, no amounts had been accrued for this matter at September 30, 2018 . Walter Energy . We were a member of the Walter Energy federal tax consolidated group, through December 14, 2006, at which time the company was spun-off from Walter Industries. Until our spin-off from Walter Energy, we joined in the filing of the Walter Energy consolidated federal income tax return for each taxable year during which we were a member of the consolidated group. As a result, we are jointly and severally liable for the federal income tax liability, if any, of the consolidated group for each of those years. Accordingly, we could be liable in the event any such federal income tax liability is incurred, and not discharged, by any other member of the Walter Energy tax consolidated group for any period during which we were included in the Walter Energy tax consolidated group. In July 2015, Walter Energy filed for bankruptcy protection under Chapter 11 of the U.S. Bankruptcy Code in the Northern District of Alabama (“Chapter 11 Case”). On February 2, 2017, the Chapter 11 Case was converted to a liquidation proceeding under Chapter 7 of the U.S. Bankruptcy Code, pursuant to which Walter Energy is now in the process of being wound down and liquidated. The IRS is currently alleging that Walter Energy owes substantial amounts for prior taxable periods in which we were a member of the Walter Energy tax consolidated group (specifically, 1983-1994, 2000-2002 and 2005). On January 11, 2016, the IRS filed a proof of claim in the Chapter 11 Case, alleging that Walter Energy owes taxes,interest and penalties for the years 1983-1994, 2000-2002 and 2005 in an aggregate amount of $554.3 million ( $229.1 million of which the IRS claims is entitled to priority status in the Chapter 11 Case). The IRS asserts that its claim is based on an alleged settlement of Walter Energy’s tax liability for years1983 through1994, which Walter Energy disputed. In the proof of claim, the IRS included an alternative calculation in an aggregate amount of $860.4 million , which it asserts would be appropriate in the event the alleged settlement is determined to be non-binding ( $535.3 million of which the IRS claims is entitled to priority status in the Chapter 11 Case). The IRS has indicated its intent to pursue collection of amounts included in the proofs of claim from former members of the Walter Energy tax consolidated group. According to a quarterly report on Form 10-Q filed by Walter Energy with the SEC on November 5, 2015, Walter Energy had $33.0 million of accruals at September 30, 2015 for unrecognized tax benefits in connection with the matters subject to the IRS claims and Walter Energy stated it believed it had sufficient accruals to address any claims, including interest and penalties, and did not believe that any potential difference between any final settlements and amounts accrued would have a material effect on Walter Energy’s financial position, but such potential difference could be material to its results of operations in a future reporting period. We have been working constructively with the parties involved in this matter in an effort to reach a consensual resolution with respect to the alleged tax liabilities at issue. Based on our work to date, we believe that once certain anticipated refunds (applicable primarily to 1997 and 2006 through 2015) are applied against asserted income tax liabilities owing for other years, the total net tax liabilities of Walter Energy, if any, will be substantially less than those asserted by the IRS. We cannot estimate the amount of, or the extent to which we will be responsible for, any liabilities to which we may be subject relating to these tax claims. Such liabilities could have a material adverse effect on our business, financial condition, liquidity or results of operations. Furthermore, there can be no assurance we will be able to reach any resolution with the parties involved in this matter and, in such event, we would intend to vigorously assert any and all available defenses against any liabilities we may have as a member of the Walter Energy consolidated group. Indemnifications . We are a party to contracts in which it is common for us to agree to indemnify third parties for certain liabilities that arise out of or relate to the subject matter of the contract. In some cases, this indemnity extends to related liabilities arising from the negligence of the indemnified parties, but usually excludes any liabilities caused by gross negligence or willful misconduct. We cannot estimate the potential amount of future payments under these indemnities until events arise that would trigger a liability under the indemnities. Additionally, in connection with the sale of assets and the divestiture of businesses, such as the divestitures of U.S. Pipe and Anvil, we may agree to indemnify buyers and related parties for certain losses or liabilities incurred by these parties with respect to: (i) the representations and warranties made by us to these parties in connection with the sale and (ii) liabilities related to the pre-closing operations of the assets or business sold. Indemnities related to pre-closing operations generally include certain environmental and tax liabilities and other liabilities not assumed by these parties in the transaction. Indemnities related to the pre-closing operations of sold assets or businesses normally do not represent additional liabilities to us, but simply serve to protect these parties from potential liability associated with our obligations existing at the time of the sale. As with any liability, we have accrued for those pre-closing obligations that are considered probable and reasonably estimable. Should circumstances change, increasing the likelihood of payments related to a specific indemnity, we will accrue a liability when future payment is probable and the amount is reasonably estimable. Other Matters. We monitor and analyze our warranty experience and costs periodically and may revise our warranty reserves as necessary. Critical factors in our reserve analyses include warranty terms, specific claim situations, general incurred and projected failure rates, the nature of product failures, product and labor costs, and general business conditions. In 2017, our warranty analysis identified certain Technologies radio products produced prior to 2017 and installed in particularly harsh environments that had been failing at higher-than-expected rates. During the quarter ended March 31, 2017, we conducted additional testing of these products and revised our estimates of warranty expenses. As a result, we recorded an additional warranty expense of $9.8 million in the second quarter of 2017. During the quarter ended June 30, 2018, we completed a similar analysis and determined, based on this new information, that certain other Technologies products had been failing at higher-than-expected rates as well, and that the average cost to repair or replace certain products under warranty was higher than previously estimated. As a result, in the third quarter of 2018, we recorded an additional warranty expense of $14.1 million associated with such products. We are party to a number of other lawsuits arising in the ordinary course of business, including product liability cases for products manufactured by us or third parties. We provide for costs relating to these matters when a loss is probable and the amount is reasonably estimable. Administrative costs related to these matters are expensed as incurred. The effect of the outcome of these matters on our future financial statements cannot be predicted with certainty as any such effect depends on the amount and timing of the resolution of such matters. While the results of litigation cannot be predicted with certainty, we believe that the final outcome of such other litigation is not likely to have a materially adverse effect on our business or prospects. Operating Leases. We maintain operating leases primarily for equipment and facilities. Rent expense was $6.4 million , $5.8 million and $5.8 million for 2018 , 2017 and 2016 , respectively. Future minimum payments under non-cancellable operating leases are $4.3 million , $3.9 million , $3.5 million , $3.0 million and $2.0 million during 2019 , 2020 , 2021 , 2022 and 2023 , respectively. Total minimum payments due beyond 2023 are $3.2 million

Subsequent Events

Subsequent Events	12 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On October 25, 2018 , our board of directors declared a dividend of $0.05 per share on our common stock, payable on or about November 20, 2018 to stockholders of record at the close of business on November 9, 2018 . In October, 2018, we announced the closure our Middleborough, Massachusetts location and the creation of a center of excellence for research and development in Atlanta, Georgia. The estimated cost of this reorganization is approximately $5.0 million . In November 2018, we announced our intention to acquire Krausz Industries, Ltd, a manufacturer of pipe couplings, grips and clamps for approximately $140.0 million

Quarterly Consolidated Financia

Quarterly Consolidated Financial Information (Unaudited)	12 Months Ended
	Sep. 30, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Consolidated Financial Information (Unaudited) Quarter Fourth Third Second First (in millions, except per share amounts) 2018 Net sales $ 254.3 $ 250.2 $ 233.2 $ 178.3 Gross profit 85.5 74.5 74.5 55.4 Operating income 40.5 30.6 29.9 20.7 Income from continuing operations 25.0 15.3 10.2 55.1 Net income 25.0 15.3 10.2 55.1 Earnings per basic share (1) Continuing operations 0.16 0.10 0.06 0.35 Net income 0.16 0.10 0.06 0.35 Earnings per diluted share (1) Continuing operations 0.16 0.10 0.06 0.34 Net income 0.16 0.10 0.06 0.34 2017 Net sales $ 226.9 $ 232.2 $ 199.7 $ 167.2 Gross profit 81.0 82.6 52.5 51.8 Operating income 33.6 43.0 11.3 14.2 Income from continuing operations 20.1 24.1 4.7 5.4 Discontinued operations (0.8 ) (0.1 ) 68.6 1.3 Net income 19.3 24.0 73.3 6.7 Earnings per basic share (1) Continuing operations 0.13 0.15 0.03 0.03 Discontinued operations (0.01 ) — 0.43 0.01 Net income 0.12 0.15 0.46 0.04 Earnings per diluted share (1) Continuing operations 0.13 0.15 0.03 0.03 Discontinued operations (0.01 ) — 0.42 0.01 Net income 0.12 0.15 0.45 0.04 (1)

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition -Revenue is recognized when delivery of products has occurred or services have been rendered and there is persuasive evidence of a sales arrangement, selling prices are fixed or determinable and collectibility is reasonably assured. Revenue is reported net of estimated discounts, returns and rebates as “net sales.”
Share-based Compensation	Stock-based Compensation- Compensation expense for stock-based awards granted to employees and directors is based on the fair value at the grant dates for our stock-settled share awards and is based on the fair value at each reporting date for our cash-settled share awards. See Note 11.
Cash and Cash Equivalents	Cash and Cash Equivalents-All highly liquid investments with remaining maturities of 90 days or less when purchased are classified as cash equivalents. Where there is no right of offset against cash balances, outstanding checks are included in accounts payable.
Receivables	Receivables- Receivables are amounts due from customers. To reduce credit risk, credit investigations are generally performed prior to accepting orders from new customers and, when necessary, letters of credit, bonds or other instruments are required to ensure payment.
Inventory Supplies, Policy	Other Current Assets- Other current assets include maintenance supplies and tooling costs. Costs for perishable tools and maintenance items are expensed when put into service. Costs for more durable items are amortized over their estimated useful lives, ranging from 3 to 10
Inventories	Inventories-Inventories are recorded at the lower of first-in, first-out method cost or estimated net realizable value. We evaluate our inventory in terms of excess and obsolete exposures. This evaluation includes such factors as anticipated usage, inventory turnover, inventory levels and ultimate product sales value. Inventory cost includes an overhead component that is affected by levels of production and actual costs incurred. We periodically evaluate the effects of production levels and costs capitalized as part of inventory.
Property, Plant and Equipment	Property, Plant and Equipment- Property, plant and equipment is recorded at cost, less accumulated depreciation. Depreciation is recorded using the straight-line method over the estimated useful lives of the assets. Estimated useful lives are 10 to 20 years for land improvements, 10 to 40 years for buildings and 3 to 15 years for machinery and equipment. Leasehold improvements and capitalized leases are depreciated using the straight-line method over the lesser of the useful life of the asset or the remaining lease term. Gains and losses upon disposition are reflected in operating results in the period of disposition. Direct internal and external costs to implement computer systems and internal-use software are capitalized. Capitalized costs are depreciated over the estimated useful life of the system or software, generally 6 years, beginning when site installation or module development is complete and ready for use. Liabilities are recognized at fair value for asset retirement obligations related to plant and landfill closures in the period in which they are reasonably estimable and the carrying amounts of the related long-lived assets are correspondingly increased. Over time, the liabilities are accreted to their estimated future values. At September 30, 2018 and 2017 , asset retirement obligations were $4.1 million and $3.8 million , respectively. During 2016, FASB issued Accounting Standards Update 2016-02 Leases
Accounting for the Impairment of Long-Lived Assets	Accounting for the Impairment of Long-Lived Assets- We test indefinite-lived intangible assets and goodwill for impairment annually (or more frequently if events or circumstances indicate possible impairment.) We perform our annual impairment testing at September 1. We amortize finite-lived intangible assets over their respective estimated useful lives and review for impairment if events or circumstances indicate possible impairment.
Workers Compensation	Workers Compensation- Our exposure to workers compensation claims is generally limited to $1 million per incident. Liabilities, including those related to claims incurred but not reported, are recorded principally using annual valuations based on discounted future expected payments and using historical data combined with insurance industry data when historical data is limited. We are indemnified under an agreement with a predecessor to Tyco for all Mueller Co. and Anvil workers compensation liabilities related to incidents that occurred prior to August 16, 1999. See Note 17. We retained U.S. Pipe workers compensation liabilities related to incidents that occurred prior to the segment's April 1, 2012 sale date, but the purchaser agreed to reimburse us for up to $11.8 million in payments we make related to these liabilities. At September 30, 2018 , the remaining reimbursement receivable may be up to $4.5 million , which we have recorded on a discounted basis as $1.2 million in other current assets and $3.3 million in other noncurrent assets. On an undiscounted basis, workers compensation liabilities were $9.1 million and $10.7 million at September 30, 2018 and 2017 , respectively. On a discounted basis, workers compensation liabilities were $7.7 million and $9.1 million at September 30, 2018 and 2017 , respectively.
Warranty Costs	Warranty Costs- We accrue for warranty expenses that can include costs of repair and/or replacement, including labor, materials, equipment, freight and reasonable overhead costs. We accrue for the estimated cost of product warranties at the time of sale if such costs are determined to be probable and reasonably estimable at that time. We monitor and analyze our warranty experience and costs periodically and may revise our warranty reserves as necessary. Critical factors in our reserve analyses include warranty terms, specific claim situations, general incurred and projected failure rates, the nature of product failures, product and labor costs, and general business conditions. As discussed in Note 17. we recognized $14.1 million and $9.8 million of Technologies' warranty expense during the years ended September 30, 2018 and 2017
Deferred Financing Fees	Deferred Financing Costs- Costs of debt financing are charged to expense over the lives of the related financing agreements. Remaining costs and the future period over which they would be charged to expense are reassessed when amendments to the related financing agreements or prepayments occur. ABL Agreement deferred financing costs are included in other noncurrent assets and other deferred financing costs are offset against long-term debt in the accompanying consolidated balance sheets. Deferred financing costs of $7.4 million at September 30, 2018 are scheduled to amortize as follows: $0.8 million related to the ABL Agreement amortizes on a straight-line basis; $6.6 million related to the Senior Unsecured Notes amortizes using the effective-interest rate method. All such amortization will be over the remaining term of the respective debt. See Note 7.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities- We managed interest rate risk to some extent using derivative instruments. We had designated our interest rate swap contracts as cash flow hedges of interest payments. As a result, the changes in the fair value of these contracts prior to settlement were reported as a component of accumulated other comprehensive loss and were reclassified into earnings in the periods during which the hedged transactions affected earnings. We recorded a cash gain of $2.4 million in the quarter ended June 30, 2018 upon termination of the interest rate swaps.
Income Taxes	Income Taxes- Deferred tax liabilities and deferred tax assets are recognized for the expected future tax consequences of events that have been included in the financial statements or tax returns. Such liabilities and assets are determined based on the differences between the financial statement basis and the tax basis of assets and liabilities, using tax rates in effect for the years in which the differences are expected to reverse. A valuation allowance is provided when, based upon the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. We only record tax benefits for positions that management believes are more likely than not of being sustained under audit based solely on the technical merits of the associated tax position. The amount of tax benefit recognized for any position that meets the more likely than not threshold is the largest amount of the tax benefit that we believe is greater than 50% likely of being realized. On December 22, 2017, HR-1, commonly referred to as the Tax Cuts and Jobs Act (“Act”), was enacted, which made significant revisions to federal income tax laws, including lowering the corporate income tax rate to 21% from 35% effective January 1, 2018, overhauling the taxation of income earned outside the United States and eliminating or limiting certain deductions. The Act subjects us to current tax on global intangible low-taxed income (“GILTI”) earned by certain of our foreign subsidiaries. The Act states that we can make an accounting policy election to either recognize deferred taxes for temporary differences expected to reverse as GILTI in future years or provide for the tax expense related to GILTI in the year the tax is incurred. We have elected to recognize the tax on GILTI as a period expense in the period the tax is incurred. In September 2018, we adopted Accounting Standards Update 2018-02 Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which permits, but does not require, companies to reclassify from accumulated other comprehensive loss to retained earnings any “stranded tax effects” caused by the Act. We have elected to not make such a reclassification.
Environmental Expenditures	Environmental Expenditures- We capitalize environmental expenditures that increase the life or efficiency of noncurrent assets or that reduce or prevent environmental contamination. We accrue for environmental expenses resulting from existing conditions that relate to past operations when the costs are probable and reasonably estimable. We are indemnified under an agreement with a predecessor to Tyco for certain environmental liabilities that existed at August 16, 1999. See Note 17.
Research and Development	Research and Development-Research and development costs are expensed as incurred.
Advertising	Advertising-Advertising costs are expensed as incurred.
Translation of Foreign Currency	Translation of Foreign Currency- Assets

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Schedule of Credit Losses for Financing Receivables, Current [Table Text Block]	The following table summarizes information concerning our allowance for credit losses. 2018 2017 2016 (in millions) Balance at beginning of year $ 4.1 $ 4.5 $ 3.9 Provision charged to expense 0.5 0.3 0.6 Balances written off, net of recoveries (0.7 ) (0.8 ) — Other 0.1 0.1 — Balance at end of year $ 4.0 $ 4.1 $ 4.5
Schedule of Reserves for Excess and Obsolete Inventory	The following table summarizes information concerning our inventory valuation reserves. 2018 2017 2016 (in millions) Balance at beginning of year $ 4.4 $ 4.6 $ 4.4 Provision charged to expense 2.2 2.0 2.1 Inventory disposed (1.2 ) (2.1 ) (2.1 ) Other (0.3 ) (0.1 ) 0.2 Balance at end of year $ 5.1 $ 4.4 $ 4.6
Schedule of Product Warranty Liability	Activity in accrued warranty, reported as part of both other current liabilities and other noncurrent liabilities, is presented below. 2018 2017 2016 (in millions) Balance at beginning of year $ 8.5 $ 2.0 $ 2.9 Warranty accruals 18.7 12.3 5.3 Warranty costs (7.2 ) (5.8 ) (6.2 ) Balance at end of year $ 20.0 $ 8.5 $ 2.0

Business Combination (Tables)

Business Combination (Tables)	12 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Schedule of Business Acquisitions, by Acquisition [Table Text Block]	On February 15, 2017, we acquired Singer Valve, a manufacturer of automatic control valves, and its affiliates for aggregate cash consideration of $26.6 million , net of post-closing adjustments. Singer Valve had net sales of approximately $15 million in calendar 2016 and is included in Infrastructure. The allocation of consideration to the assets and liabilities of these companies, is presented below, in millions. Assets acquired, net of cash: Receivables $ 3.0 Inventories 5.8 Other current assets 0.2 Property, plant and equipment 1.0 Intangible assets 11.4 Goodwill 7.2 Liabilities assumed: Accounts payable 0.7 Other current liabilities 0.4 Current and long term debt 0.1 Deferred income tax liability 0.8 Consideration paid $ 26.6

Discontinued Operations, Asse_2

Discontinued Operations, Assets Held for Sale and Divestitures (Tables)	12 Months Ended
	Sep. 30, 2017
Discontinued Operations and Disposal Groups [Abstract]
Disposal Group, Details of Gain on Sale [Table Text Block]	The table below presents a summary of the sale of Anvil, in millions. Gross cash proceeds $ 305.7 Noncash proceeds 1.9 Total proceeds 307.6 Transaction expenses (8.3 ) Net proceeds 299.3 Assets and liabilities disposed (189.8 ) Gain on sale, pre-tax 109.5 Income tax (41.6 ) Gain on sale, net of tax $ 67.9
Schedule of Discontinued Operations Income (Loss) [Table Text Block]	The table below presents a summary of the operating results for the Anvil discontinued operations. These operating results do not reflect what they would have been had Anvil not been classified as discontinued operations. 2017 2016 (in millions) Net sales $ 83.1 $ 338.3 Cost of sales 62.8 241.9 Gross profit 20.3 96.4 Operating expenses: Selling, general and administrative 17.2 67.6 Other charges 0.2 1.1 Total operating expenses 17.4 68.7 Operating income 2.9 27.7 Interest expense, net — — Income before income taxes 2.9 27.7 Income tax expense 1.8 8.9 1.1 18.8 Gain on sale, net of tax 67.9 — Income from discontinued operations $ 69.0 $ 18.8

Identifiable Intangible Assets

Identifiable Intangible Assets (Tables)	12 Months Ended
	Sep. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Intangible Assets and Goodwill [Table Text Block]	Intangible assets are presented below. September 30, 2018 2017 (in millions) Capitalized internal-use software: Cost $ 27.6 $ 28.4 Accumulated amortization (14.2 ) (11.3 ) Net book value 13.4 17.1 Business combination-related: Cost: Finite-lived intangible assets: Technology 82.6 76.7 Customer relationships and other 358.8 359.2 Indefinite-lived intangible assets: Trade names and trademarks 266.6 266.8 Goodwill 12.1 12.9 720.1 715.6 Accumulated amortization: Technology (72.9 ) (72.2 ) Customer relationships and other (240.4 ) (221.2 ) (313.3 ) (293.4 ) Net book value 406.8 422.2 Total intangible assets net book value $ 420.2 $ 439.3

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Schedule of Income before Income Tax, Domestic and Foreign	The components of income before income taxes from continuing operations are presented below. 2018 2017 2016 (in millions) U.S. $ 97.3 $ 82.7 $ 69.7 Non-U.S. (1.6 ) (4.2 ) (0.4 ) Income before income taxes $ 95.7 $ 78.5 $ 69.3
Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]	The components of income tax (benefit) expense from continuing operations are presented below. 2018 2017 2016 (in millions) Current: U.S. federal $ 25.7 $ 25.4 $ 28.9 U.S. state and local 7.1 4.0 2.0 Non-U.S. 0.6 0.5 (0.1 ) 33.4 29.9 30.8 Deferred: U.S. federal (42.6 ) (4.3 ) (9.8 ) U.S. state and local (1.0 ) (0.2 ) 3.4 Non-U.S. 0.3 (1.2 ) (0.2 ) (43.3 ) (5.7 ) (6.6 ) Income tax (benefit) expense $ (9.9 ) $ 24.2 $ 24.2
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	The reconciliation between income tax expense at the U.S. federal statutory income tax rate and reported income tax expense from continuing operations is presented below. 2018 2017 2016 (in millions) Expense at U.S. federal statutory income tax rates of 24.5%, 35% and 35%, respectively $ 23.4 $ 27.5 $ 24.3 Adjustments to reconcile to income tax expense: State income taxes, net of federal benefit 4.8 2.7 3.1 Domestic production activities deduction (2.4 ) (4.5 ) (3.0 ) Tax credits (1.7 ) (1.4 ) (2.0 ) Nondeductible expenses, other than compensation 0.5 0.6 0.7 Valuation allowances 0.5 0.4 — Foreign income taxes — 0.3 0.2 Nondeductible compensation 0.2 0.5 0.4 Excess tax benefits related to stock compensation (0.6 ) (2.1 ) (0.5 ) Federal tax rate change (42.5 ) (0.4 ) 0.4 Federal transition tax 7.5 — — Other 0.4 0.6 0.6 Income tax (benefit) expense $ (9.9 ) $ 24.2 $ 24.2
Schedule of Deferred Tax Assets and Liabilities	Deferred income tax balances are presented below. September 30, 2018 2017 (in millions) Deferred income tax assets: Inventory reserves $ 10.4 $ 12.0 Accrued expenses 13.3 14.9 Pension — 6.0 Stock-based compensation 3.3 6.2 State net operating losses 3.2 3.2 Federal credit carryovers 2.1 0.9 Other 1.0 2.7 33.3 45.9 Valuation allowance (1.9 ) (1.5 ) Total deferred income tax assets, net of valuation allowance 31.4 44.4 Deferred income tax liabilities: Intangible assets 95.7 151.2 Pension 2.3 — Other 11.4 7.2 Total deferred income tax liabilities 109.4 158.4 Net deferred income tax liabilities $ 78.0 $ 114.0 Balance sheet presentation: Deferred income taxes $ 79.2 $ 115.1 Less deferred tax assets included in other noncurrent assets 1.2 1.1 Net deferred income tax liabilities $ 78.0 $ 114.0
Summary of Unrecognized Tax Benefits	The following table summarizes information concerning our gross unrecognized tax benefits. 2018 2017 (in millions) Balance at beginning of year $ 3.0 $ 2.8 Increases related to prior year positions 0.1 0.1 Increases related to current year positions 0.3 0.2 Decreases due to lapse in statute of limitations (0.1 ) (0.1 ) Balance at end of year $ 3.3 $ 3.0

Borrowing Arrangements (Tables)

Borrowing Arrangements (Tables)	12 Months Ended
	Sep. 30, 2018
Long-term Debt and Capital Lease Obligations [Abstract]
Components of Long-Term Debt	The components of our long-term debt are presented below. September 30, 2018 2017 (in millions) 5.5% Senior Notes $ 450.0 $ — ABL Agreement — — Term Loan — 484.8 Other 1.6 1.7 451.6 486.5 Deferred financing costs (6.6 ) (5.9 ) Less current portion (0.7 ) (5.6 ) Long-term debt $ 444.3 $ 475.0

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Sep. 30, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The fair values of the swap contracts are presented below. September 30, 2018 2017 (in millions) Interest rate swap contracts, designated as cash flow hedges: Other current liabilities $ — $ 1.2 Other noncurrent liabilities — 1.3 $ — $ 2.5 Currency swap contracts, not designated as hedges: Other noncurrent liabilities $ 0.9 $ 1.3

Derivative Financial Instrume_3

Derivative Financial Instruments Fair Vale of Derivatives Table (Tables)	12 Months Ended
	Sep. 30, 2018
Derivatives, Fair Value [Line Items]
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block]	The fair values of the swap contracts are presented below. September 30, 2018 2017 (in millions) Interest rate swap contracts, designated as cash flow hedges: Other current liabilities $ — $ 1.2 Other noncurrent liabilities — 1.3 $ — $ 2.5 Currency swap contracts, not designated as hedges: Other noncurrent liabilities $ 0.9 $ 1.3

Retirement Plans (Tables)

Retirement Plans (Tables)	12 Months Ended
	Sep. 30, 2018
Defined Benefit Plan [Abstract]
Schedule of Net Periodic Benefit Cost	During March 2017, the Financial Accounting Standards Board issued Accounting Standards Update No. 2017-07 (“ASU 2017-07”). ASU 2017-07 required us to exclude from operating income the components of net periodic benefit cost other than service cost. We adopted ASU 2017-07 on October 1, 2017, and this adoption required reclassification of pension costs other than service in the 2017 and 2016 results, which has the effect of increasing operating income by those amounts. The components of net periodic benefit cost for our Pension Plans are presented below. 2018 2017 2016 (in millions) Service cost $ 1.8 $ 2.0 $ 1.7 Components of net periodic benefit cost excluded from operating income following adoption of ASU 2017-07: Interest cost 14.3 14.3 18.9 Expected return on plan assets (16.5 ) (16.9 ) (19.7 ) Amortization of actuarial net loss 3.2 4.0 3.4 Pension settlement — — 16.6 Other — — 0.1 Pension costs other than service 1.0 1.4 19.3 Net periodic benefit cost $ 2.8 $ 3.4 $ 21.0
Schedule of Accumulated and Projected Benefit Obligations	Balance sheet information for Pension Plans with accumulated benefit obligations in excess of plan assets is presented below. September 30, 2018 2017 (in millions) Projected benefit obligations $ 6.2 $ 379.5 Accumulated benefit obligations 6.2 379.5 Fair value of plan assets 5.0 364.2 Balance sheet information for Pension Plans with accumulated benefit obligations less than plan assets is presented below. September 30, 2018 2017 (in millions) Projected benefit obligations $ 327.1 $ 1.0 Accumulated benefit obligations 327.1 1.0 Fair value of plan assets 338.5 2.1
Schedule Of Defined Benefit Plans Disclosures	Amounts recognized for Pension Plans are presented below. Pension Plans 2018 2017 (in millions) Projected benefit obligations: Beginning of year $ 380.5 $ 403.1 Service cost 1.8 2.0 Interest cost 14.3 14.3 Actuarial gain (38.6 ) (14.5 ) Benefits paid (24.3 ) (24.8 ) Currency translation (0.3 ) 0.4 Decrease in obligation due to curtailment / settlement — — End of year $ 333.4 $ 380.5 Accumulated benefit obligations at end of year $ 333.4 $ 380.5 Plan assets: Beginning of year $ 366.3 $ 340.0 Actual return on plan assets 2.0 15.8 Employer contributions — 35.0 Currency translation (0.3 ) 0.4 Benefits paid (24.3 ) (24.8 ) Other (0.2 ) (0.1 ) End of year $ 343.5 $ 366.3 Accrued benefit cost at end of year: Funded (unfunded) status $ 10.1 $ (14.2 ) Recognized on balance sheet: Other noncurrent assets $ 11.2 $ 1.1 Other current liabilities (1.1 ) (1.1 ) Other noncurrent liabilities — (14.2 ) $ 10.1 $ (14.2 ) Recognized in accumulated other comprehensive loss, before tax: Prior year service cost $ — $ — Net actuarial loss 66.0 93.4 $ 66.0 $ 93.4
Schedule of Pension and Other Postretirement Benefits Activity in Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Pension Plan activity in accumulated other comprehensive loss, before tax, in 2018 is presented below, in millions. Balance at beginning of year $ 93.4 Actuarial gain (24.2 ) Prior year actuarial loss amortization to net periodic cost (3.2 ) Balance at end of year $ 66.0
Schedule of Assumptions Used	A summary of key assumptions for our Pension Plans is below. Pension Plans 2018 2017 2016 Weighted average used to determine benefit obligations: Discount rate 4.37 % 3.88 % 3.68 % Weighted average used to determine net periodic cost: Discount rate 3.88 % 3.68 % 3.92 % Expected return on plan assets 4.68 % 5.16 % 5.50 %
Schedule of Strategic Allocation of Plan Assets [Table Text Block]	This trust’s strategic asset allocations, tactical range at September 30, 2018 and actual asset allocations are presented below. Strategic asset allocation Actual asset allocations at September 30, Tactical range 2018 2017 2016 Fixed income investments 80 % 75 80 % 77 % 78 % 69 % Equity investments 20 15 - 20 % 21 21 29 Cash — 0 - 5 % 2 1 2 100 % 100 % 100 % 100 %
Schedule of Allocation of Plan Assets	The assets of the Pension Plans by level within the fair value hierarchy are presented below. September 30, 2018 Level 1 Level 2 Total (in millions) Fixed income $ — $ 264.1 $ 264.1 Equity: Large cap stocks: Large cap index funds — 30.5 30.5 Mid cap stocks: Mid cap index funds — 10.1 10.1 Small cap stocks: Small cap growth funds — 10.0 10.0 International stocks: Mutual funds 11.8 — 11.8 International funds — 10.3 10.3 Total equity 11.8 60.9 72.7 Cash and cash equivalents 6.6 — 6.6 $ 18.4 $ 325.0 $ 343.4 September 30, 2017 Level 1 Level 2 Total (in millions) Fixed income $ — $ 284.4 $ 284.4 Equity: Large cap stocks: Large cap growth funds $ — $ 32.6 $ 32.6 Mid cap stocks: Mid cap index funds — 10.9 10.9 Small cap stocks: Small cap growth funds — 11.3 11.3 International stocks: Mutual funds 15.4 — 15.4 International funds — 7.4 7.4 Total equity 15.4 62.2 77.6 Cash and cash equivalents 4.3 — 4.3 $ 19.7 $ 346.6 $ 366.3
Schedule of Expected Benefit Payments	Our estimated future pension benefit payments are presented below in millions. 2019 $ 31.2 2020 25.0 2021 24.8 2022 24.5 2023 24.2 2024-2028 113.6

Capital Stock (Tables)

Capital Stock (Tables)	12 Months Ended
	Sep. 30, 2018
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Schedule of Common Stock Outstanding Roll Forward [Table Text Block]	Common stock share activity is presented below. Shares outstanding at September 30, 2015 160,497,841 Vesting of restricted stock units, net of shares withheld for taxes 370,138 Exercise of stock options 270,599 Exercise of employee stock purchase plan instruments 218,475 Settlement of performance-based restricted stock units, net of shares withheld for taxes 335,998 Shares outstanding at September 30, 2016 161,693,051 Vesting of restricted stock units, net of shares withheld for taxes 262,488 Exercise of stock options 905,834 Exercise of employee stock purchase plan instruments 150,174 Settlement of performance-based restricted stock units, net of shares withheld for taxes 160,063 Stock repurchased under buyback program (4,581,227 ) Shares outstanding at September 30, 2017 158,590,383 Vesting of restricted stock units, net of shares withheld for taxes 232,875 Exercise of stock options 851,628 Exercise of employee stock purchase plan instruments 150,669 Settlement of performance-based restricted stock units, net of shares withheld for taxes 86,516 Stock repurchased under buyback program (2,573,475 ) Other (6,475 ) Shares outstanding at September 30, 2018 157,332,121

Stock-based Compensation Plans

Stock-based Compensation Plans (Tables)	12 Months Ended
	Sep. 30, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	The effect of stock-based compensation on our statements of operations, including discontinued operations, is presented below. 2018 2017 2016 (in millions, except per share data) Decrease in operating income $ 6.4 $ 8.6 $ 9.1 Decrease in net income 4.0 4.8 5.8 Decrease in earnings per basic share 0.03 0.03 0.04 Decrease in earnings per diluted share 0.03 0.03 0.04
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	Restricted stock unit activity under the 2006 Plan is summarized below. Restricted stock units Weighted average grant date fair value per unit Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 872,790 $ 8.45 0.8 Granted 360,255 9.33 Vested (510,535 ) 7.94 $ 4.7 Cancelled (59,062 ) 8.23 Outstanding at September 30, 2016 663,448 9.34 1.0 Granted 343,860 13.05 Vested (359,797 ) 9.34 4.7 Cancelled (21,681 ) 13.26 Outstanding at September 30, 2017 625,830 11.23 0.9 Granted 276,658 12.20 Vested (342,038 ) 10.84 4.2 Cancelled (78,888 ) 11.41 Outstanding at September 30, 2018 481,562 12.14 1.0
Schedule of Nonvested Performance-based Units Activity [Table Text Block]	Stock-settled PRSUs activity under the 2006 Plan is summarized below. Award date Settlement year Performance period Grant date per unit fair value Units awarded Units forfeited Net units Performance factor Shares earned December 3, 2013 2017 2014 $ 8.52 90,841 (4,401 ) 86,440 2.000 172,880 2015 $ 9.78 90,841 (4,401 ) 86,440 0.000 — 2016 $ 9.38 90,849 (7,402 ) 83,447 1.021 85,199 December 2, 2014 2018 2015 $ 9.78 80,233 (3,835 ) 76,398 0.000 — 2016 $ 9.38 80,229 (6,447 ) 73,782 1.021 75,327 2017 $ 13.26 80,229 (11,673 ) 68,556 1.000 68,556 December 1, 2015 2019 2016 $ 9.38 77,823 (3,998 ) 73,825 1.021 75,375 2017 $ 13.26 77,824 (3,997 ) 73,827 1.000 73,827 2018 $ 12.50 77,824 (61,841 ) 15,983 1.357 21,689 November 29, 2016 2020 2017 $ 13.26 59,285 (5,279 ) 54,006 1.000 54,006 2018 $ 12.50 59,286 (39,910 ) 19,376 1.357 26,294 2019 59,290 (39,909 ) 19,381 January 23, 2017 2020 2017 $ 13.15 19,012 — 19,012 1.000 19,012 2018 $ 12.50 19,011 — 19,011 1.357 25,798 2019 19,011 — 19,011 November 28, 2017 2021 2018 $ 12.50 57,092 — 57,092 1.357 77,474 2019 57,092 — 57,092 2020 57,104 — 57,104
Schedule of Share-based Compensation. Options	Stock option activity under the 2006 Plan is summarized below. Options Weighted average exercise price per option Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 3,992,666 $ 6.54 4.2 $ 9.3 Exercised (270,599 ) 6.83 0.8 Cancelled (167,759 ) 17.82 Outstanding at September 30, 2016 3,554,308 5.99 3.4 23.8 Exercised (905,834 ) 4.71 7.3 Cancelled (207,820 ) 14.72 Outstanding at September 30, 2017 2,440,654 5.72 2.5 17.3 Exercised (851,628 ) 7.00 3.8 Cancelled — — Outstanding at September 30, 2018 1,589,026 $ 5.03 1.9 $ 10.3 Exercisable at September 30, 2018 1,589,026 $ 5.03 1.9 $ 10.3
Schedule of Share-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range [Table Text Block]	The ranges of exercise prices for stock options outstanding at September 30, 2018 are summarized below. Exercise price Options Weighted average exercise price Weighted average remaining contractual term (years) Exercisable options Weighted average exercise price $ 0.00 - $ 4.99 555,319 $ 3.32 2.4 555,319 $ 3.32 $ 5.00 - $ 9.99 1,033,707 5.95 1.6 1,033,707 5.95 1,589,026 $ 5.03 1.9 1,589,026 $ 5.03
Schedule of Share-based Compensation, Phantom Award, Activity	Phantom Plan activity is summarized below. Phantom Plan units Weighted average grant date fair value per unit Weighted average remaining contractual term (years) Aggregate intrinsic value (millions) Outstanding at September 30, 2015 558,878 $ 6.22 0.8 Granted 302,875 9.84 Vested (270,822 ) $ 3.1 Cancelled (56,905 ) 9.28 Outstanding at September 30, 2016 534,026 9.60 0.9 Granted 199,260 13.22 Vested (278,000 ) 3.7 Cancelled (103,279 ) 10.87 Outstanding at September 30, 2017 352,007 11.36 0.9 Granted 163,199 12.40 Vested (170,675 ) 2.1 Cancelled (81,758 ) 12.10 Outstanding at September 30, 2018 262,773 12.12 0.6

Supplemental Balance Sheet In_2

Supplemental Balance Sheet Information (Tables)	12 Months Ended
	Sep. 30, 2018
Balance Sheet Related Disclosures [Abstract]
Schedule Of Selected Supplemental Balance Sheet Information [Table Text Block]	Selected supplemental balance sheet information is presented below. September 30, 2018 2017 (in millions) Inventories: Purchased components and raw material $ 81.6 $ 67.7 Work in process 37.8 35.6 Finished goods 37.2 35.6 $ 156.6 $ 138.9 Other current assets: Maintenance and repair tooling $ 3.5 $ 3.3 Income taxes 1.6 10.9 Other 12.4 10.2 $ 17.5 $ 24.4 Property, plant and equipment: Land $ 5.4 $ 5.6 Buildings 55.9 53.4 Machinery and equipment 311.4 266.7 Construction in progress 22.2 24.7 $ 394.9 $ 350.4 Accumulated depreciation (244.0 ) (228.1 ) $ 150.9 $ 122.3 Other current liabilities: Compensation and benefits $ 31.7 $ 26.9 Customer rebates 9.7 6.5 Taxes other than income taxes 3.3 3.2 Warranty 6.0 3.5 Environmental 1.2 1.3 Income taxes 7.6 0.9 Interest 8.0 0.6 Restructuring 0.9 3.3 Other 8.0 7.3 $ 76.4 $ 53.5

Supplemental Statement of Ope_2

Supplemental Statement of Operations Information (Tables)	12 Months Ended
	Sep. 30, 2018
Supplemental Income Statement Elements [Abstract]
Schedule of Operations, Supplemental Disclosures [Table Text Block]	Selected supplemental statement of operations information is presented below. 2018 2017 2016 (in millions) Included in selling, general and administrative expenses: Research and development $ 11.6 $ 12.1 $ 9.9 Advertising $ 7.1 $ 5.2 $ 4.0 Interest expense, net: Term Loan $ 14.4 $ 19.1 $ 20.5 Deferred financing costs amortization 1.6 1.8 1.9 ABL Agreement 0.6 0.8 1.1 Interest rate swap contracts 0.6 1.9 — 5.5% Senior Notes 7.5 — — Other interest expense 0.6 0.6 0.5 25.3 24.2 24.0 Interest income (4.4 ) (2.0 ) (0.4 ) $ 20.9 $ 22.2 $ 23.6

Accumulated Other Comprehensi_2

Accumulated Other Comprehensive Loss (Tables)	12 Months Ended
	Sep. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Accumulated other comprehensive loss is presented below. Foreign currency translation Pension liability, net of tax Derivative instruments, net of tax Total (in millions) Balance at September 30, 2017 $ (3.3 ) $ (47.0 ) $ (1.5 ) $ (51.8 ) Other comprehensive income before reclassifications (3.0 ) 17.9 — 14.9 Amounts reclassified out of accumulated other comprehensive loss — 2.6 1.5 4.1 Other comprehensive income (3.0 ) 20.5 1.5 19.0 Balance at September 30, 2018 $ (6.3 ) $ (26.5 ) $ — $ (32.8 )

Supplemental Cash Flow Inform_2

Supplemental Cash Flow Information (Tables)	12 Months Ended
	Sep. 30, 2018
Supplemental Cash Flow Information [Abstract]
Schedule of Cash Flow, Supplemental Disclosures	Supplemental cash flow information is presented below. September 30, 2018 2017 2016 (in millions) Cash paid, net: Interest $ 8.9 $ 19.5 $ 21.1 Income taxes $ 10.7 $ 31.9 $ 27.1

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas	Geographical area information is presented below. United States Canada Other Total (in millions) Net sales: 2018 $ 812.2 $ 71.7 $ 32.1 $ 916.0 2017 732.0 62.3 31.7 826.0 2016 716.5 57.1 27.0 800.6 Property, plant and equipment, net: September 30, 2018 $ 144.8 $ 3.4 $ 2.7 $ 150.9 September 30, 2017 116.1 3.0 3.2 122.3
Schedule Of Selected Supplemental Balance Sheet Information		Summarized financial information for our segments is presented below. Infrastructure Technologies Corporate Total (in millions) Net sales, excluding intercompany: 2018 $ 818.8 $ 97.2 $ — $ 916.0 2017 739.9 86.1 — 826.0 2016 715.7 84.9 — 800.6 Intercompany sales: 2018 $ — $ — $ — $ — 2017 — — — — 2016 5.8 — — 5.8 Operating income (loss): 2018 $ 180.1 $ (24.4 ) $ (34.0 ) $ 121.7 2017 163.8 (20.3 ) (41.4 ) 102.1 2016 162.5 (11.1 ) (39.2 ) 112.2 Depreciation and amortization: 2018 $ 37.4 $ 6.1 $ 0.2 $ 43.7 2017 36.3 5.2 0.4 41.9 2016 34.2 4.8 0.5 39.5 Total pension settlement and other charges: 2018 $ 0.1 $ 0.1 $ 10.3 $ 10.5 2017 2.7 0.7 7.0 10.4 2016 1.0 0.9 5.8 7.7 Capital expenditures: 2018 $ 47.3 $ 8.3 $ 0.1 $ 55.7 2017 28.5 11.4 0.7 40.6 2016 24.3 7.0 0.2 31.5 Total assets: September 30, 2018 $ 843.9 $ 87.1 $ 360.9 $ 1,291.9 September 30, 2017 792.6 88.4 377.3 1,258.3 Intangible assets, net: September 30, 2018 $ 396.9 $ 23.3 $ — $ 420.2 September 30, 2017 417.2 22.1 — 439.3

Quarterly Consolidated Financ_2

Quarterly Consolidated Financial Information (Unaudited) (Tables)	12 Months Ended
	Sep. 30, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	Quarter Fourth Third Second First (in millions, except per share amounts) 2018 Net sales $ 254.3 $ 250.2 $ 233.2 $ 178.3 Gross profit 85.5 74.5 74.5 55.4 Operating income 40.5 30.6 29.9 20.7 Income from continuing operations 25.0 15.3 10.2 55.1 Net income 25.0 15.3 10.2 55.1 Earnings per basic share (1) Continuing operations 0.16 0.10 0.06 0.35 Net income 0.16 0.10 0.06 0.35 Earnings per diluted share (1) Continuing operations 0.16 0.10 0.06 0.34 Net income 0.16 0.10 0.06 0.34 2017 Net sales $ 226.9 $ 232.2 $ 199.7 $ 167.2 Gross profit 81.0 82.6 52.5 51.8 Operating income 33.6 43.0 11.3 14.2 Income from continuing operations 20.1 24.1 4.7 5.4 Discontinued operations (0.8 ) (0.1 ) 68.6 1.3 Net income 19.3 24.0 73.3 6.7 Earnings per basic share (1) Continuing operations 0.13 0.15 0.03 0.03 Discontinued operations (0.01 ) — 0.43 0.01 Net income 0.12 0.15 0.46 0.04 Earnings per diluted share (1) Continuing operations 0.13 0.15 0.03 0.03 Discontinued operations (0.01 ) — 0.42 0.01 Net income 0.12 0.15 0.45 0.04 (1)

Organization (Details)

Organization (Details) $ in Millions	Jul. 31, 2014	Sep. 30, 2018USD ($)business_segments
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization		Organization Mueller Water Products, Inc., a Delaware corporation, together with its consolidated subsidiaries, operates in two business segments: Infrastructure and Technologies. Infrastructure (previously referred to as “Mueller Co.”) manufactures valves for water and gas systems, including butterfly, iron gate, tapping, check, knife, plug, automatic control and ball valves, as well as dry-barrel and wet-barrel fire hydrants. Technologies (previously referred to as “Mueller Technologies”) offers metering systems, leak detection, pipe condition assessment and other products and services for the water infrastructure industry. The “Company,” “we,” “us” or “our” refer to Mueller Water Products, Inc. and its subsidiaries. With regard to the Company’s segments, “we,” “us” or “our” may also refer to the segment being discussed. In July 2014 , Infrastructure acquired a 49% ownership in an industrial valve joint-venture for $1.7 million . Due to substantive control features in the joint-venture agreement, all of the joint venture’s assets, liabilities and results of operations are included in our consolidated financial statements. We included an adjustment for the income attributable to noncontrolling interest in selling, general and administrative expenses. Noncontrolling interest is recorded at its carrying value, which approximates fair value. Our consolidated financial statements are prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), which require us to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, sales and expenses and the disclosure of contingent assets and liabilities for the reporting periods. Actual results could differ from those estimates. All significant intercompany balances and transactions have been eliminated. Certain reclassifications have been made to previously reported amounts to conform to the current presentation.
Number of Reportable Segments | business_segments		2
Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage	49.00%
Payments to Acquire Interest in Joint Venture | $		$ 1.7

Summary of Significant Accoun_4

Summary of Significant Accounting Policies (Schedule of Allowance for Doubtful Receivables) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of year	$ 4.1	$ 4.5	$ 3.9
Provision for Doubtful Accounts	0.5	0.3	0.6
Balances written off, net of recoveries	(0.7)	(0.8)	0
Reclassifications	0.1	0.1	0
Balance at end of year	$ 4	$ 4.1	$ 4.5

Summary of Significant Accoun_5

Summary of Significant Accounting Policies (Schedule of Reserves for Excess and Obsolete Inventory) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 4.4	$ 4.6	$ 4.4
Provision charged to expense	(2.2)	(2)	(2.1)
Inventory disposed	(1.2)	(2.1)	(2.1)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Increase (Decrease) Adjustment	(0.3)	(0.1)	0.2
Balance at end of year	$ 5.1	$ 4.4	$ 4.6

Summary of Significant Accoun_6

Summary of Significant Accounting Policies (Schedule of Product Warranty Liability) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Accounting Policies [Abstract]
Balance at end of year	$ 20	$ 8.5	$ 2	$ 2.9
Movement in Standard Product Warranty Accrual [Roll Forward]
Balance at beginning of year	3.5
Product Warranty Expense	18.7	12.3	5.3
Warranty payments	(7.2)	(5.8)	$ (6.2)
Balance at end of year	$ 6	$ 3.5

Summary of Significant Accoun_7

Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Jan. 06, 2017	Sep. 30, 2014
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$ 2.4	$ 0	$ 0
Product Warranty Expense	18.7	12.3	$ 5.3
Asset Retirement Obligation	4.1	3.8
Exposure to Workers Compensation Claims, Per Incident	1
Discontinued Operations, Receivable from Buyer of Discontinued Operation				$ 1.9	$ 11.8
Workers Compensation Undiscounted Basis Liability	9.1	10.7
Workers' Compensation Liability	$ 7.7	9.1
Income Tax Benefit, Likelihood of Realization Threshold	50.00%
Debt Issuance Costs, Net	$ 7.4
Minimum [Member]
Finite-Lived Tangible Asset, Useful Life, Maximum	3 years
Maximum [Member]
Finite-Lived Tangible Asset, Useful Life, Maximum	10 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	10 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	20 years
Building [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	10 years
Building [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	40 years
Machinery and Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life, Minimum	3 years
Machinery and Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	15 years
Software and Software Development Costs [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life, Minimum	6 years
U.S. Pipe [Member] | Maximum [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation		4.5
Other Current Assets [Member] | U.S. Pipe [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation		1.2
Other Noncurrent Assets [Member] | U.S. Pipe [Member]
Discontinued Operations, Receivable from Buyer of Discontinued Operation		3.3
Revolving Credit Facility [Member]
Debt Issuance Costs, Net	$ 0.8
Secured Debt [Member]
Debt Issuance Costs, Net	6.6	5.9
Unsecured Debt [Member]
Debt Issuance Costs, Net	6.6
Product Concentration Risk [Member]
Product Warranty Expense	$ 14.1	$ 9.8

Business Combination Narrative

Business Combination Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 26.6
Business Acquisition, Revenue Reported by Acquired Entity for Last Annual Period		$ 15

Business Combination Schedule o

Business Combination Schedule of Business Acquisitions, by Acquisition (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Feb. 15, 2017
Assets acquired:
Receivables			$ 3
Inventories			5.8
Other current assets			0.2
Property, plant and equipment			1
Customer relationships and other identifiable intangible assets			11.4
Goodwill	$ 12.9	$ 12.1	7.2
Accounts payable and other current liabilities			0.7
Other current liabilities			0.4
Current and long term debt			0.1
Deferred income tax liability			$ 0.8
Payments to Acquire Businesses, Gross	$ 26.6

Discontinued Operations, Asse_3

Discontinued Operations, Assets Held for Sale and Divestitures Narrative (Details) $ in Millions	Jan. 06, 2017USD ($)
Disposal Group, Including Discontinued Operation, Consideration	$ 305.7

Discontinued Operations, Asse_4

Discontinued Operations, Assets Held for Sale and Divestitures Disposal Group, detail of Gain on Sale (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Jan. 06, 2017	Sep. 30, 2014
Disposal Group, Details of Gain on Sale [Line Items]
Disposal Group, Including Discontinued Operation, Consideration				$ 305.7
Discontinued Operations, Receivable from Buyer of Discontinued Operation				1.9	$ 11.8
Total proceeds				307.6
Transaction expenses				(8.3)
Net proceeds				299.3
Assets and liabilities disposed				$ (189.8)
Gain on sale, pre-tax	$ 109.5
Income tax	$ (41.6)
Gain on sale, net of tax		$ 67.9	$ 0

Discontinued Operations, Asse_5

Discontinued Operations, Assets Held for Sale and Divestitures Schedule of Discontinued Operations Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net sales						$ 83.1	$ 338.3
Cost of sales						62.8	241.9
Gross profit						20.3	96.4
Selling, general and administrative						17.2	67.6
Other charges						0.2	1.1
Total operating expenses						17.4	68.7
Operating income						2.9	27.7
Interest expense, net						0	0
Income before income taxes						2.9	27.7
Income before income taxes			$ (109.5)
Income tax expense						1.8	8.9
Discontinued Operation, Income (Loss) from Discontinued Operation During Phase-out Period, Net of Tax						1.1	18.8
Gain on sale, net of tax						67.9	0
Income from discontinued operations	$ (0.8)	$ (0.1)	$ 68.6	$ 1.3	$ 0	$ 69	$ 18.8

Identifiable Intangible Asset_2

Identifiable Intangible Assets Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Amortization	$ 22.8	$ 22.1	$ 21.2
Software and Software Development Costs [Member]
Finite-Lived Intangible Asset, Useful Life	6 years
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	2 years 9 months 18 days
Amortization	$ 2.9	2.4	1.9
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3.5
Finite-Lived Intangible Assets, Amortization Expense, Year Two	3.2
Finite-Lived Intangible Assets, Amortization Expense, Year Three	2.5
Finite-Lived Intangible Assets, Amortization Expense, Year Four	2
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 1.5
Business Combination-Related Identifiable Intangible [Member]
Finite-Lived Intangible Asset, Useful Life	6 years 9 months 18 days
Amortization	$ 19.9	$ 19.7	$ 19.3
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	20.7
Finite-Lived Intangible Assets, Amortization Expense, Year Two	20.7
Finite-Lived Intangible Assets, Amortization Expense, Year Three	20.6
Finite-Lived Intangible Assets, Amortization Expense, Year Four	20.5
Finite-Lived Intangible Assets, Amortization Expense, Year Five	$ 20.5

Identifiable Intangible Asset_3

Identifiable Intangible Assets Schedule of Intangible Assets and Goodwill (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017	Feb. 15, 2017
Indefinite-lived intangible assets:
Goodwill	$ 12.1	$ 12.9	$ 7.2
Intangible Assets, Gross (Excluding Goodwill)	720.1	715.6
Accumulated amortization:
Accumulated Amortization	313.3	293.4
Intangible Assets, Net (Including Goodwill)	420.2	439.3
Business Combination-Related Identifiable Intangible [Member]
Accumulated amortization:
Net book value	406.8	422.2
Trademarks and Trade Names [Member]
Indefinite-lived intangible assets:
Trade names and trademarks	266.6	266.8
Software and Software Development Costs [Member]
Capitalized external-use software:
Capitalized Computer Software, Gross	27.6	28.4
Accumulated amortization	14.2	11.3
Net book value	13.4	17.1
Technology-Based Intangible Assets [Member]
Finite-lived intangible assets:
Technology	82.6	76.7
Accumulated amortization:
Accumulated Amortization	72.9	72.2
Customer Relationships [Member]
Finite-lived intangible assets:
Customer relationships and other	358.8	359.2
Accumulated amortization:
Accumulated Amortization	$ 240.4	$ 221.2

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount		$ (42.5)	$ (0.4)	$ 0.4
Transition Tax Expense	$ 7.5
Effective Income Tax Rate Reconciliation, Federal Transition Tax, Amount		7.5	0	0
Unrecognized Tax Benefits, Interest on Income Taxes Accrued		0.6	0.7
Income tax expense (benefit)		(9.9)	$ 24.2	$ 24.2
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit		0.8
Deferred Tax Assets, Tax Credit Carryforwards, Foreign		$ 4.5

Income Taxes (Income before Inc

Income Taxes (Income before Income Tax, Domestic and Foreign) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Loss before income taxes, U.S.	$ 97.3	$ 82.7	$ 69.7
Loss before income taxes, Non-U.S.	(1.6)	(4.2)	(0.4)
Net Income Before Income Tax	$ 95.7	$ 78.5	$ 69.3

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Current:
Current Federal Tax Expense (Benefit)	$ 25.7	$ 25.4	$ 28.9
Current State and Local Tax Expense (Benefit)	7.1	4	2
Current Foreign Tax Expense (Benefit)	0.6	0.5	(0.1)
Current Income Tax Expense (Benefit)	33.4	29.9	30.8
Deferred:
Deferred Federal Income Tax Expense (Benefit)	(42.6)	(4.3)	(9.8)
Deferred State and Local Income Tax Expense (Benefit)	(1)	(0.2)	3.4
Deferred Foreign Income Tax Expense (Benefit)	0.3	(1.2)	(0.2)
Deferred Income Tax Expense (Benefit)	(43.3)	(5.7)	(6.6)
Income tax expense (benefit)	$ (9.9)	$ 24.2	$ 24.2

Income Taxes (Disposal Groups,

Income Taxes (Disposal Groups, including Discontinued Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)	$ (9.9)	$ 24.2	$ 24.2

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Statutory Taxes to Effective Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Tax at U.S. federal statutory income tax rate of 35%	$ 23.4	$ 27.5	$ 24.3
Adjustments to reconcile to income tax expense (benefit):
Federal Valuation Allowance	0.5	0.4	0
State income taxes, net of federal benefit	4.8	2.7	3.1
Domestic production activities deduction	(2.4)	(4.5)	(3)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	(42.5)	(0.4)	0.4
Federal transition tax	7.5	0	0
Excess tax benefits related to stock compensation	(0.6)	(2.1)	(0.5)
Tax Credits	(1.7)	(1.4)	(2)
Other nondeductible expenses	0.5	0.6	0.7
Foreign income taxes	0	0.3	0.2
Nondeductible compensation	0.2	0.5	0.4
Other income tax	0.4	0.6	0.6
Income tax expense (benefit)	$ (9.9)	$ 24.2	$ 24.2

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Deferred income tax assets:
Inventory reserves	$ 10.4	$ 12
Accrued expenses	13.3	14.9
Pension and other postretirement benefits	0	6
Stock-based compensation	3.3	6.2
State net operating losses	3.2	3.2
Federal net operating losses and credit carryovers	2.1	0.9
All other	1	2.7
Deferred income tax assets	33.3	45.9
Valuation allowance	(1.9)	(1.5)
Total deferred income tax assets	31.4	44.4
Deferred income tax liabilities:
Identifiable intangible assets	(95.7)	(151.2)
Pension and other postretirement benefits	2.3	0
Other	(11.4)	(7.2)
Total deferred income tax liabilities	109.4	158.4
Net deferred income tax liabilities	78	114
Deferred Tax Liabilities, Gross, Noncurrent	79.2	115.1
Included in other noncurrent assets	$ 1.2	$ 1.1

Income Taxes (Gross Unrecognize

Income Taxes (Gross Unrecognized Tax Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year	$ 3	$ 2.8
Increases related to prior year positions	0.1	0.1
Increases related to current year positions	0.3	0.2
Decreases due to lapse in statute of limitations	(0.1)	(0.1)
Balance at end of year	$ 3.3	$ 3

Income Taxes (Summary of Valuat

Income Taxes (Summary of Valuation Allowance) (Details) $ in Millions	Sep. 30, 2018USD ($)
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 1.5
Balance at end of year	$ 1.9

Borrowing Arrangements (Narrati

Borrowing Arrangements (Narrative) (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended			84 Months Ended
	Jun. 30, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Nov. 25, 2021
Agreement termination date		Jul. 13, 2021
Unsecured Debt		$ 451.6	$ 486.5
Loss on early extinguishment of debt	$ (6.2)	6.5	0	$ 0
Future maturities of outstanding borrowings
CY plus 1		0.7
CY plus 2		0.6
CY plus 3		0.3
CY plus 4		0
CY plus 5		0
Payments of Financing Costs		6.9	1	$ 1.2
Revolving Credit Facility [Member]
Revolving credit facility amount		175	225
Potential increase size of the credit facility by an additional amount		$ 150
Line of Credit Facility, Interest Rate at Period End		12500.00%
Aggregate commitments availability		$ 17.5
Aggregate commitments availability, percentage		10.00%
Outstanding letter of credit accrued fees and expenses		$ 18.3
Excess availability reduced by outstanding borrowings, outstanding letters of credit and accrued fees and expenses		125
Unsecured Debt		$ 0	0
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		2500.00%
Loss on early extinguishment of debt		$ (0.3)
Bonds [Member]
Debt Instrument, Interest Rate, Effective Percentage		5.50%
Future maturities of outstanding borrowings
Financial Liabilities Fair Value Disclosure		$ 452.3
Unsecured Debt [Member]
Deferred Finance Costs, Noncurrent, Gross		6.6
Unsecured Debt		450	0
Swing Line Loans [Member]
Revolving credit facility amount		25
Letter Of Credit [Member]
Revolving credit facility amount		$ 60
Secured Debt [Member]
Borrowing rate in addition to LIBOR		25000.00%
Unsecured Debt		$ 0	$ 484.8
Long-term Debt, Gross		$ 500
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Revolving Credit Facility [Member]
Borrowing rate in addition to LIBOR		12500.00%
London Interbank Offered Rate (LIBOR) [Member] | Minimum [Member] | Secured Debt [Member]
Debt Instrument, Interest Rate, Stated Percentage		0.75%
London Interbank Offered Rate (LIBOR) [Member] | Maximum [Member] | Revolving Credit Facility [Member]
Borrowing rate in addition to LIBOR		15000.00%
Base Rate [Member] | Minimum [Member] | Revolving Credit Facility [Member]
Borrowing rate in addition to LIBOR		2500.00%
Base Rate [Member] | Maximum [Member] | Revolving Credit Facility [Member]
Borrowing rate in addition to LIBOR		5000.00%
Scenario, Forecast [Member] | Secured Debt [Member]
Agreement termination date					Nov. 25, 2021

Borrowing Arrangements (Compone

Borrowing Arrangements (Components Of Long-Term Debt) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Unsecured Debt	$ 451.6	$ 486.5
Debt Issuance Costs, Net	(7.4)
Current portion of long-term debt	(0.7)	(5.6)
Long-term debt, excluding current maturities	444.3	475
Revolving Credit Facility [Member]
Unsecured Debt	0	0
Debt Issuance Costs, Net	(0.8)
Secured Debt [Member]
Unsecured Debt	0	484.8
Debt Issuance Costs, Net	(6.6)	(5.9)
Other [Member]
Unsecured Debt	1.6	1.7
Unsecured Debt [Member]
Unsecured Debt	450	$ 0
Debt Issuance Costs, Net	$ (6.6)

Derivative Financial Instrume_4

Derivative Financial Instruments (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Maturity Date	Sep. 30, 2021
Derivative, Cap Interest Rate	0.75%
Derivative, Fixed Interest Rate		2.341%
Derivative, Notional Amount		$ 150
Secured Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative, Amount of Hedged Item	$ 150
Cash Flow Hedging [Member] | Secured Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt Instrument, Interest Rate, Effective Percentage	4.841%
Foreign Exchange Contract [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other noncurrent liabilities	$ 0.9	1.3
Interest Rate Swap [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other current liabilities	0	1.2
Other noncurrent liabilities	0	1.3
Derivative Liability	$ 0	$ 2.5

Derivative Financial Instrume_5

Derivative Financial Instruments Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Gain (Loss) on Discontinuation of Interest Rate Cash Flow Hedge Due to Forecasted Transaction Probable of Not Occurring, Net	$ 2.4	$ 0	$ 0

Retirement Plans (Narrative) (D

Retirement Plans (Narrative) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)			$ (3.2)	$ (4)	$ (3.4)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement					$ 16.6
Defined Benefit Plan, Description					75%
Defined Benefit Plan, Plan Assets, Payment for Settlement					$ 58.5
Defined Benefit Plan, Plan Assets, Contributions by Employer			0	35
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment			$ 0	0	(16.6)
Percentage of Obligations Related to U.S. Plan			98.00%
Payment for Pension Benefits			$ 0	35	0
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage			100.00%
Defined Contribution Plan, Cost			$ 4.7	$ 4.1	$ 4
Percentage of Assets Related to U.S. Plan			98.00%
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Expected Return on Plan Assets Major Asset Classes Time Horizon			10
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan Expected Return on Plan Assets Major Asset Classes Time Horizon			15 years
Pension Plan, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate			4.37%	3.88%	3.68%
Discount rate			3.88%	3.68%	3.92%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage			20.00%		30.00%	40.00%
Equity Securities [Member] | Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage			15.00%
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)		$ (2)
Payment for Pension Benefits		$ 1.2
Defined Contribution Plan, Cost	$ 0.4

Retirement Plans (Net Periodic

Retirement Plans (Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Service cost	$ 1.8	$ 2	$ 1.7
Interest cost	14.3	14.3	18.9
Expected return on plan assets	(16.5)	(16.9)	(19.7)
Amortization of net loss (gain)	3.2	4	3.4
Curtailment / special settlement loss (gain)	0	0	16.6
Other	0	0	0.1
Defined Benefit Plan, Net Periodic Benefit Cost other than Service Cost	1	1.4	19.3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	2.8	3.4	$ 21
Pension Plan, Defined Benefit [Member]
Service cost	1.8	2
Interest cost	$ 14.3	$ 14.3

Retirement Plans (Accumulated a

Retirement Plans (Accumulated and Projected Benefit Obligations) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Pension Plans with accumulated benefit obligations in excess of plan assets
Projected benefit obligation	$ 6.2	$ 379.5
Accumulated benefit obligation	6.2	379.5
Fair value of plan assets	5	364.2
Pension plans with plan assets in excess of accumulated benefit obligations
Projected benefit obligation	327.1	1
Accumulated benefit obligation	327.1	1
Fair value of plan assets	$ 338.5	$ 2.1

Retirement Plans (Amounts Recog

Retirement Plans (Amounts Recognized for Pension and Other Postretirement Benefit Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Projected benefit obligations:
Service cost	$ 1.8	$ 2	$ 1.7
Interest cost	14.3	14.3	18.9
Plan assets:
Beginning of year	366.3
Defined Benefit Plan, Plan Assets, Contributions by Employer	0	35
Settlement			(58.5)
End of year	343.4	366.3
Recognized in accumulated other comprehensive loss, before tax:
Other	(0.2)	(0.1)
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other current liabilities	(1.1)	(1.1)
Projected benefit obligations:
Beginning of year	380.5	403.1
Service cost	1.8	2
Interest cost	14.3	14.3
Actuarial loss (gain)	(38.6)	(14.5)
Benefits paid	(24.3)	(24.8)
Currency translation	(0.3)	0.4
Decrease in obligation due to curtailment / settlement	0	0
End of year	333.4	380.5	403.1
Accumulated benefit obligation at end of year	333.4	380.5
Plan assets:
Beginning of year	366.3	340
Actual return on plan assets	2	15.8
Currency translation	(0.3)	0.4
Benefits paid	(24.3)	(24.8)
End of year	343.5	366.3	$ 340
Accrued benefit cost at end of year:
Unfunded status	10.1	(14.2)
Recognized on balance sheet:
Other noncurrent assets	11.2	1.1
Other noncurrent liabilities	0	(14.2)
Amount recognized on balance sheet	10.1	(14.2)
Recognized in accumulated other comprehensive loss, before tax:
Prior year service cost (gain)	0	0
Net actuarial loss (gain)	66	93.4
Recognized in accumulated other comprehensive loss, before tax	$ 66	$ 93.4

Retirement Plans (Pension and O

Retirement Plans (Pension and Other Postretirement Benefits Activity in Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement		$ 16.6
Prior year actuarial loss amortization to net periodic cost	$ 2.6
Other	4.1
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Balance at beginning of year	93.4
Balance at beginning of year	93.4
Actuarial gain	(24.2)
Prior year service loss amortization to net periodic cost	(3.2)
Balance at end of year	$ 66

Retirement Plans (Components of

Retirement Plans (Components of Accumulated Other Comprehensive Income (Loss) Related to Pension and Other Postretirement Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other		$ 4.1
Defined Benefit Plan, Amortization of Gain (Loss)		3.2	$ 4	$ 3.4
Pension Plan, Defined Benefit [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		(3.2)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		24.2
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax		$ 66	$ 93.4
Scenario, Forecast [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)	$ 2

Retirement Plans (Assumptions U

Retirement Plans (Assumptions Used) (Details)	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Pension Plan, Defined Benefit [Member]
Weighted average used to determine benefit obligations:
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	4.37%	3.88%	3.68%
Weighted average used to determine net periodic cost:
Discount rate	3.88%	3.68%	3.92%
Expected return on plan assets	4.68%	5.16%	5.50%
Minimum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan Expected Return on Plan Assets Major Asset Classes Time Horizon	10

Retirement Plans (Strategic All

Retirement Plans (Strategic Allocation of Plan Assets) (Details)	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	100.00%
Actual asset allocations
Actual plan asset allocations	100.00%	100.00%	100.00%
Equity Securities [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	20.00%		30.00%	40.00%
Actual asset allocations
Actual plan asset allocations	21.00%	21.00%	29.00%
Fixed Income Securities [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	80.00%
Fixed Income Funds [Member]
Actual asset allocations
Actual plan asset allocations	77.00%	78.00%	69.00%
Cash and Cash Equivalents [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Actual asset allocations
Actual plan asset allocations	2.00%	1.00%	2.00%
Minimum [Member] | Equity Securities [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	15.00%
Minimum [Member] | Fixed Income Funds [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	75.00%
Minimum [Member] | Cash and Cash Equivalents [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	0.00%
Maximum [Member] | Fixed Income Funds [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	80.00%
Maximum [Member] | Cash and Cash Equivalents [Member]
Strategic asset allocation
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage	5.00%

Retirement Plans (Fair Value As

Retirement Plans (Fair Value Asset Allocation) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 343.4	$ 366.3
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18.4	19.7
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	325	346.6
Mid- Cap Growth Funds [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.1	10.9
Mid- Cap Growth Funds [Member] [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Mid- Cap Growth Funds [Member] [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.1	10.9
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	72.7	77.6
Equity Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.8	15.4
Equity Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	60.9	62.2
Large Cap Growth Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		32.6
Large Cap Growth Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		0
Large Cap Growth Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets		32.6
Large Cap Index Funds [Member] [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.5
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0
Large Cap Index Funds [Member] [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	30.5
Small Cap Growth Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	11.3
Small Cap Growth Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Small Cap Growth Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10	11.3
Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.8	15.4
Mutual Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	11.8	15.4
Mutual Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Stocks [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.3	7.4
International Stocks [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
International Stocks [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10.3	7.4
Fixed Income Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	264.1	284.4
Fixed Income Funds [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	0	0
Fixed Income Funds [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	264.1	284.4
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.6	4.3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	6.6	4.3
Cash and Cash Equivalents [Member] | Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 0	$ 0

Retirement Plans (Expected Bene

Retirement Plans (Expected Benefit Payments) (Details) $ in Millions	Sep. 30, 2018USD ($)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated benefit payments, CY plus 1	$ 31.2
Estimated benefit payments, CY plus 2	25
Estimated benefit payments, CY plus 3	24.8
Estimated benefit payments, CY plus 4	24.5
Estimated benefit payments, CY plus 5	24.2
Estimated benefit payments, CY plus 6 and up	$ 113.6

Retirement Plans Schedule of Am

Retirement Plans Schedule of Amounts Expected to Amortize from AOCI to net income in the coming year (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)		$ (3.2)	$ (4)	$ (3.4)
Scenario, Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Amortization of Gain (Loss)	$ (2)

Capital Stock (Details)

Capital Stock (Details) - shares	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Outstanding Shares [Roll Forward]
Shares outstanding	158,590,383	161,693,051	160,497,841
Exercised stock options	851,628	905,834	270,599
Exercise of employee stock purchase plan	150,669	150,174	218,475
Vesting of restricted stock units, net of shares withheld for taxes	232,875	262,488	370,138
Treasury Stock, Shares, Acquired	(6,475)
Shares outstanding	157,332,121	158,590,383	161,693,051
Stock repurchased under buyback program	(2,573,475)	(4,581,227)
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		160,063
Performance Shares [Member]
Outstanding Shares [Roll Forward]
Settlement of performance-based restricted stock units, net of shares withheld for taxes	146,061	263,410
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period	86,516		335,998

Stock-based Compensation Plan_2

Stock-based Compensation Plans (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015	Dec. 14, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	214,435	238,826	867,065
Weighted-average recognition period, Compensation expense related to stock awards not yet vested	1 year 4 months 13 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 5.1
Number of shares authorized under a Plan					20,500,000
Shares available for future grants under a Plan	7,410,033
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	10 years
Share-based Compensation, Expected Forfeiture Rate	2.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Phantom Share Units (PSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Settlement of performance-based restricted stock units, net of shares withheld for taxes	170,675	278,000	270,822
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	163,199	199,260	302,875
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 12.12	$ 11.36	$ 9.60	$ 6.22
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instrument Other than Option, Nonvested, Intrinsic Value	$ 11.51
Share-based compensation liability	$ 3
Employee Stock [Member]
Number of shares authorized under a Plan		5,800,000
Shares available for future grants under a Plan		2,750,935
Price for shares offered under ESPP, as a percentage of closing price on the first or last day of the offering period	85.00%
Performance Shares [Member]
Settlement of performance-based restricted stock units, net of shares withheld for taxes	146,061	263,410
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
Settlement of performance-based restricted stock units, net of shares withheld for taxes	342,038	359,797	510,535
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	276,658	343,860	360,255
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value	$ 12.14	$ 11.23	$ 9.34	$ 8.45
Minimum [Member] | Performance Shares [Member]
Performance Factor	0
Maximum [Member] | Performance Shares [Member]
Performance Factor	2

Stock-based Compensation Plan_3

Stock-based Compensation Plans (Schedule of Share-based Compensation, Effect on Statement of Operations) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Decrease in operating income	$ 6.4	$ 8.6	$ 9.1
Effect on net income or loss	$ (4)	$ (4.8)	$ (5.8)
Effect on earnings or loss per basic share	$ (0.03)	$ (0.03)	$ (0.04)
Effect on earnings or loss per diluted share	$ (0.03)	$ (0.03)	$ (0.04)

Stock-based Compensation Plan_4

Stock-based Compensation Plans (Schedule of Share-based Compensation, Restricted Stock Units Activity) (Details) - Restricted Stock Units (RSUs) [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSUs, Outstanding, Number	481,562	625,830	663,448	872,790
Outstanding, Weighted average grant date fair value per share	$ 12.14	$ 11.23	$ 9.34	$ 8.45
Outstanding, Weighted average remaining contractual term	1 year	27 days	1 year	24 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	276,658	343,860	360,255
Granted, Weighted average grant date fair value per share	$ 12.20	$ 13.05	$ 9.33
Settlement of performance-based restricted stock units, net of shares withheld for taxes	342,038	359,797	510,535
RSUs, Vested in Period, Weighted Average Grant Date Fair Value	$ 10.84	$ 9.34	$ 7.94
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 4.2	$ 4.7	$ 4.7
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(78,888)	(21,681)	(59,062)
Canceled, Weighted average grant date fair value per share	$ 11.41	$ 13.26	$ 8.23

Stock-based Compensation Plan_5

Stock-based Compensation Plans (Schedule of Shared-Based Compensation, Performance Units (Details)

3 Months Ended

12 Months Ended

Dec. 31, 2017shares

Mar. 31, 2017shares

Dec. 31, 2016shares

Dec. 31, 2015shares

Dec. 31, 2014shares

Dec. 31, 2013shares

Sep. 30, 2021shares

Sep. 30, 2020shares

Sep. 30, 2019shares

Sep. 30, 2018$ / sharesshares

Sep. 30, 2017$ / sharesshares

Sep. 30, 2016$ / sharesshares

Sep. 30, 2015$ / sharesshares

Sep. 30, 2014$ / sharesshares

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period

160,063

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period

86,516

335,998

Settlement of performance-based restricted stock units, net of shares withheld for taxes

146,061

263,410

Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

57,092

2014 [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 9.38

$ 9.78

$ 8.52

2014 [Member] | Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

2

Settlement of performance-based restricted stock units, net of shares withheld for taxes

172,880

2014 [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

90,841

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(4,401)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

86,440

2014 [Member] | Share-based Compensation Award, Tranche Two [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

0

Settlement of performance-based restricted stock units, net of shares withheld for taxes

0

2014 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

90,841

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(4,401)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

86,440

2014 [Member] | Share-based Compensation Award, Tranche Three [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.021

Settlement of performance-based restricted stock units, net of shares withheld for taxes

85,199

2014 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

90,849

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(7,402)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

83,447

2015 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 13.26

2015 [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 9.38

$ 9.78

2015 [Member] | Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

0

Settlement of performance-based restricted stock units, net of shares withheld for taxes

0

2015 [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

80,233

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(3,835)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

76,398

2015 [Member] | Share-based Compensation Award, Tranche Two [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.021

Settlement of performance-based restricted stock units, net of shares withheld for taxes

75,327

2015 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

80,229

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(6,447)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

73,782

2015 [Member] | Share-based Compensation Award, Tranche Three [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1

Settlement of performance-based restricted stock units, net of shares withheld for taxes

68,556

2015 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

80,229

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(11,673)

Settlement of performance-based restricted stock units, net of shares withheld for taxes

68,556

2016 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 12.50

$ 13.26

2016 [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 9.38

2016 [Member] | Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.021

2016 [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

77,823

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(3,998)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

73,825

2016 [Member] | Share-based Compensation Award, Tranche Two [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1

2016 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

77,824

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(3,997)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

73,827

2016 [Member] | Share-based Compensation Award, Tranche Three [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.357

2016 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

77,824

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(61,841)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

15,983

2017 member [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 12.50

$ 13.26

2017 member [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1

2017 member [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

59,285

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(5,279)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

54,006

2017 member [Member] | Share-based Compensation Award, Tranche Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.357

2017 member [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

59,286

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(39,910)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

19,376

2017 member [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

59,290

January 23, 2017 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 13.15

January 23, 2017 [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1

January 23, 2017 [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

19,012

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

19,012

January 23, 2017 [Member] | Share-based Compensation Award, Tranche Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.357

January 23, 2017 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

19,011

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

19,011

January 23, 2017 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

19,011

November 28, 2017 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value | $ / shares

$ 12.50

November 28, 2017 [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Performance Factor

1.357

November 28, 2017 [Member] | Share-based Compensation Award, Tranche One [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

57,092

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

November 28, 2017 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

57,092

November 28, 2017 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

57,104

Scenario, Forecast [Member] | 2016 [Member] | Share-based Compensation Award, Tranche One [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

75,375

Scenario, Forecast [Member] | 2016 [Member] | Share-based Compensation Award, Tranche Two [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

73,827

Scenario, Forecast [Member] | 2016 [Member] | Share-based Compensation Award, Tranche Three [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

21,689

Scenario, Forecast [Member] | 2017 member [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

54,006

Scenario, Forecast [Member] | 2017 member [Member] | Share-based Compensation Award, Tranche Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

26,294

Scenario, Forecast [Member] | 2017 member [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

(39,909)

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

19,381

Scenario, Forecast [Member] | January 23, 2017 [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

19,012

Scenario, Forecast [Member] | January 23, 2017 [Member] | Share-based Compensation Award, Tranche Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

25,798

Scenario, Forecast [Member] | January 23, 2017 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

19,011

Scenario, Forecast [Member] | January 23, 2017 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

Scenario, Forecast [Member] | November 28, 2017 [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

57,104

57,092

Scenario, Forecast [Member] | November 28, 2017 [Member] | Share-based Compensation Award, Tranche One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Settlement of performance-based restricted stock units, net of shares withheld for taxes

77,474

Scenario, Forecast [Member] | November 27, 2018 [Member] | Share-based Compensation Award, Tranche Two [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

Scenario, Forecast [Member] | November 27, 2018 [Member] | Share-based Compensation Award, Tranche Three [Member] | PRSU base units [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period

0

Stock-based Compensation Plan_6

Stock-based Compensation Plans (Schedule of Share-based Compensation. Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, shares	2,440,654	3,554,308	3,992,666
Outstanding, Weighted average exercise price (per share)	$ 5.03	$ 5.72	$ 5.99	$ 6.54
Outstanding, Weighted average remaining contractual term, years	1 year 10 months 24 days	2 years 6 months	3 years 4 months 24 days	4 years 2 months 12 days
Outstanding, Aggregate intrinsic value	$ 10.3	$ 17.3	$ 23.8	$ 9.3
Exercised, shares	(851,628)	(905,834)	(270,599)
Exercised, Weighted average exercise price (per share)	$ 7	$ 4.71	$ 6.83
Exercised, Aggregate intrinsic value	$ 3.8	$ 7.3	$ 0.8
Canceled, shares	0	(207,820)	(167,759)
Canceled, Weighted average exercise price (per share)	$ 0	$ 14.72	$ 17.82
Stock Options, Exercisable, Number	1,589,026
Exercisable, Weighted average exercise price (per share)	$ 5.03
Exercisable, Weighted average remaining contractual term, years	1 year 10 months 24 days
Exercisable, Aggregate intrinsic value	$ 10.3
Outstanding, shares	1,589,026	2,440,654	3,554,308	3,992,666

Stock-based Compensation Plan_7

Stock-based Compensation Plans Schedule of Share-based Compensation, Option Disclosures by Ranges of Exercise Prices (Details)	12 Months Ended
	Sep. 30, 2018$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Number of Outstanding Options | shares	1,589,026
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 5.03
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	1 year 10 months 24 days
Stock Options, Exercisable, Number | shares	1,589,026
Stock Options, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 5.03
Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Number of Outstanding Options | shares	555,319
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 3.32
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	2 years 4 months 24 days
Stock Options, Exercisable, Number | shares	555,319
Stock Options, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 3.32
Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Number of Outstanding Options | shares	1,033,707
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Exercise Price	$ 5.95
Stock Options, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term	1 year 7 months 6 days
Stock Options, Exercisable, Number | shares	1,033,707
Stock Options, Exercise Price Range, Exercisable Options, Weighted Average Exercise Price	$ 5.95
Minimum [Member] | Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Lower Range Limit	0
Minimum [Member] | Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Lower Range Limit	5
Maximum [Member] | Exercise Price Range 1 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Upper Range Limit	4.99
Maximum [Member] | Exercise Price Range 2 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Options, Exercise Price Range, Upper Range Limit	$ 9.99

Stock-based Compensation Plan_8

Stock-based Compensation Plans (Schedule of Share-based Compensation, Phantom Award Activity) (Details) - Phantom Share Units (PSUs) [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, shares	352,007	534,026	558,878
Outstanding, Weighted average grant date fair value per share	$ 12.12	$ 11.36	$ 9.60	$ 6.22
Outstanding, Weighted average remaining contractual term	18 days	27 days	27 days	24 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	163,199	199,260	302,875
Granted, Weighted average grant date fair value per share	$ 12.40	$ 13.22	$ 9.84
Vested, shares	(170,675)	(278,000)	(270,822)
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value	$ 2.1	$ 3.7	$ 3.1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	(81,758)	(103,279)	(56,905)
Canceled, Weighted average grant date fair value per share	$ 12.10	$ 10.87	$ 9.28
Outstanding, shares	262,773	352,007	534,026	558,878

Supplemental Balance Sheet In_3

Supplemental Balance Sheet Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Sep. 30, 2017
Inventories:
Purchased components and raw material	$ 81.6	$ 67.7
Work in process	37.8	35.6
Finished goods	37.2	35.6
Inventories, net	156.6	138.9
Other current assets:
Maintenance and repair tooling	3.5	3.3
Prepaid income taxes	1.6	10.9
Other	12.4	10.2
Other current assets	17.5	24.4
Property, plant and equipment:
Land	5.4	5.6
Buildings	55.9	53.4
Machinery and equipment	311.4	266.7
Construction in progress	22.2	24.7
Property, plant and equipment, gross	394.9	350.4
Accumulated depreciation	(244)	(228.1)
Property, plant and equipment, net	150.9	122.3
Other current liabilities:
Compensation and benefits	31.7	26.9
Customer rebates	9.7	6.5
Interest	8	0.6
Taxes other than income taxes	3.3	3.2
Warranty	6	3.5
Income taxes	7.6	0.9
Restructuring	0.9	3.3
Environmental	1.2	1.3
Other current liabilities	8	7.3
Accrued Liabilities, Current	$ 76.4	$ 53.5

Supplemental Statement of Ope_3

Supplemental Statement of Operations Information (Details) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Schedule of Statement of Operations Supplemental Disclosures [Line Items]
Restructuring Reserve	$ 0.9	$ 3.3
Included in selling, general and administrative expenses:
Research and development	11.6	12.1	$ 9.9
Advertising	7.1	5.2	4
Interest expense, net:
Interest rate swap contracts	0.6	1.9	0
Deferred financing fees amortization	1.6	1.8	1.9
Other interest expense	0.6	0.6	0.5
Interest Expense	25.3	24.2	24
Interest income	(4.4)	(2)	(0.4)
Interest expense, net	(20.9)	(22.2)	(23.6)
Other Cost and Expense, Operating	10.5	10.4	7.2
Secured Debt [Member]
Interest expense, net:
Debt instrument interest expense	14.4	19.1	20.5
Seven Point Three Seven Five Senior Subordinated Notes [Member]
Interest expense, net:
Debt instrument interest expense	7.5	0	0
ABL Agreement [Member]
Interest expense, net:
Debt instrument interest expense	$ 0.6	0.8	1.1
Statesboro [Member]
Interest expense, net:
Other Cost and Expense, Operating			$ 4.1
Mueller One Project [Member]
Interest expense, net:
Other Cost and Expense, Operating		$ 4.6

Accumulated Other Comprehensi_3

Accumulated Other Comprehensive Loss (Schedule Of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss), before Tax, Portion Attributable to Parent	$ (3)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(3.3)
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(47)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	(1.5)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(51.8)
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	(6.3)	$ (3.3)
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(26.5)	(47)
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax	0	(1.5)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(32.8)	(51.8)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax	(17.9)
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	14.9
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax	0
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax	2.6
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax	4.1
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Net of Tax	(1.5)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, Tax	(0.9)	(1.9)	$ 1.8
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax	(3)	2.8	0.2
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax	20.5
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax	1.5
Other Comprehensive Income (Loss), Net of Tax	$ 19	$ 16.5	$ (1)

Supplemental Cash Flow Inform_3

Supplemental Cash Flow Information (Schedule of Cash Flow, Supplemental Disclosures) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Cash paid, net:
Interest	$ 8.9	$ 19.5	$ 21.1
Income taxes	$ 10.7	$ 31.9	$ 27.1

Segment Information (Revenue an

Segment Information (Revenue and Long-Lived Assets by Geographical Areas) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 254.3	$ 250.2	$ 233.2	$ 178.3	$ 226.9	$ 232.2	$ 199.7	$ 167.2	$ 916	$ 826	$ 800.6
Intangible Assets, Net (Including Goodwill)	420.2				439.3				420.2	439.3
Total assets	1,291.9				1,258.3				$ 1,291.9	1,258.3
Document Period End Date									Sep. 30, 2018
Property, plant and equipment, net	150.9				122.3				$ 150.9	122.3
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									812.2	732	716.5
Property, plant and equipment, net	144.8				116.1				144.8	116.1
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									71.7	62.3	57.1
Property, plant and equipment, net	3.4				3				3.4	3
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									32.1	31.7	$ 27
Property, plant and equipment, net	$ 2.7				$ 3.2				$ 2.7	$ 3.2

Segment Information (Narrative)

Segment Information (Narrative) (Details) $ in Millions	12 Months Ended
	Sep. 30, 2018USD ($)business_segmentscustomer	Sep. 30, 2017USD ($)	Sep. 30, 2016
Segment Reporting [Abstract]
Number of Reportable Segments | business_segments	2
Revenue, Major Customer [Line Items]
Receivables, net	$ 164.3	$ 145.3
Intangible Assets, Net (Including Goodwill)	420.2	439.3
Total assets	$ 1,291.9	1,258.3
Document Period End Date	Sep. 30, 2018
Mueller Co. [Member]
Revenue, Major Customer [Line Items]
Intangible Assets, Net (Including Goodwill)	$ 396.9	417.2
Total assets	843.9	792.6
Mueller Technologies [Member]
Revenue, Major Customer [Line Items]
Intangible Assets, Net (Including Goodwill)	23.3	22.1
Total assets	$ 87.1	$ 88.4
Customer Concentration Risk [Member] | Major Customers, Group One
Revenue, Major Customer [Line Items]
Number of major customers | customer	10
Customer Concentration Risk [Member] | Major Customers, Group One | Sales Revenue, Net [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	54.00%
Customer Concentration Risk [Member] | Major Customers, Group Two
Revenue, Major Customer [Line Items]
Number of major customers | customer	2
Customer Concentration Risk [Member] | Major Customers, Group Two | Sales Revenue, Goods, Gross [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	34.00%
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	19.00%	18.00%	17.00%
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member] | Mueller Co. [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	18.00%
Customer Concentration Risk [Member] | Ferguson Enterprises | Sales Revenue, Goods, Gross [Member] | Mueller Technologies [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	28.00%
Customer Concentration Risk [Member] | Ferguson Enterprises | Accounts Receivable [Member]
Revenue, Major Customer [Line Items]
Receivables, net	$ 29.7	$ 20
Customer Concentration Risk [Member] | HD Supply | Sales Revenue, Goods, Gross [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	15.00%	16.00%	16.00%
Customer Concentration Risk [Member] | HD Supply | Sales Revenue, Goods, Gross [Member] | Mueller Co. [Member]
Revenue, Major Customer [Line Items]
Concentration risk, percentage of benchmark	17.00%
Customer Concentration Risk [Member] | HD Supply | Accounts Receivable [Member]
Revenue, Major Customer [Line Items]
Receivables, net	$ 31.7	$ 27.3

Segment Information (Schedule O

Segment Information (Schedule Of Selected Supplemental Balance Sheet Information) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Intercompany sales	$ 254.3	$ 250.2	$ 233.2	$ 178.3	$ 226.9	$ 232.2	$ 199.7	$ 167.2	$ 916	$ 826	$ 800.6
Operating income	40.5	$ 30.6	$ 29.9	$ 20.7	33.6	$ 43	$ 11.3	$ 14.2	121.7	102.1	112.2
Depreciation and amortization									43.7	41.9	39.5
2,016									10.5	10.4	7.7
Capital expenditures									(55.7)	(40.6)	(31.5)
Property, plant and equipment, net	150.9				122.3				150.9	122.3
Total assets	1,291.9				1,258.3				$ 1,291.9	1,258.3
Document Period End Date									Sep. 30, 2018
Intangible Assets, Net (Including Goodwill)	420.2				439.3				$ 420.2	439.3
Mueller Co. [Member]
Segment Reporting Information [Line Items]
Intercompany sales									818.8	739.9	715.7
Operating income									180.1	163.8	162.5
Depreciation and amortization									37.4	36.3	34.2
2,016									0.1	2.7	1
Capital expenditures									(47.3)	(28.5)	(24.3)
Total assets	843.9				792.6				843.9	792.6
Intangible Assets, Net (Including Goodwill)	396.9				417.2				396.9	417.2
Mueller Technologies [Member]
Segment Reporting Information [Line Items]
Intercompany sales									97.2	86.1	84.9
Operating income									(24.4)	(20.3)	(11.1)
Depreciation and amortization									6.1	5.2	4.8
2,016									0.1	0.7	0.9
Capital expenditures									(8.3)	(11.4)	(7)
Total assets	87.1				88.4				87.1	88.4
Intangible Assets, Net (Including Goodwill)	23.3				22.1				23.3	22.1
Corporate [Member]
Segment Reporting Information [Line Items]
Intercompany sales									0	0	0
Operating income									(34)	(41.4)	(39.2)
Depreciation and amortization									0.2	0.4	0.5
2,016									10.3	7	5.8
Capital expenditures									(0.1)	(0.7)	(0.2)
Total assets	360.9				377.3				360.9	377.3
Intangible Assets, Net (Including Goodwill)	$ 0				$ 0				0	0
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Intercompany sales									0	0	5.8
Intersegment Eliminations [Member] | Mueller Co. [Member]
Segment Reporting Information [Line Items]
Intercompany sales									0	0	5.8
Intersegment Eliminations [Member] | Mueller Technologies [Member]
Segment Reporting Information [Line Items]
Intercompany sales									0	0	0
Intersegment Eliminations [Member] | Corporate [Member]
Segment Reporting Information [Line Items]
Intercompany sales									$ 0	$ 0	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details) $ in Millions, $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018CAD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Loss Contingency, Damages Sought, Value					$ 10
Document Period End Date				Sep. 30, 2018	Sep. 30, 2018
Walter Energy tax assessment						$ 33
Product Warranty Expense				$ 18.7		12.3	$ 5.3
Operating Leases
Rent expense	$ 5.8		$ 5.8	6.4
Future minimum payment under non-cancelable operating leases, CY Plus 1				4.3
Future minimum payment under non-cancelable operating leases, CY Plus 2				3.9
Future minimum payment under non-cancelable operating leases, CY Plus 3				3.5
Future minimum payment under non-cancelable operating leases, CY Plus 4				3
Future minimum payment under non-cancelable operating leases, CY Plus 5				2
Future minimum payment under non-cancelable operating leases, CY plus 6 and up				3.2
IRS-Walter Energy Claim 1 Total [Member]
Loss Contingency, Damages Sought, Value		$ 554.3
IRS-Walter Energy Claim 1 Priority [Member]
Loss Contingency, Damages Sought, Value		229.1
IRS-Walter Energy Claim 2 [Member]
Loss Contingency, Damages Sought, Value		860.4
IRS-Walter Energy Claim 2 Priority [Member]
Loss Contingency, Damages Sought, Value		$ 535.3
Product Concentration Risk [Member]
Product Warranty Expense				$ 14.1		$ 9.8

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions	Nov. 20, 2018	Nov. 09, 2018	Oct. 25, 2018	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Subsequent Event [Line Items]
Dividends declared, in dollars per share					$ 0.190	$ 0.150	$ 0.100
Stock Repurchased During Period, Shares					2,573,475	4,581,227
Stock Repurchased During Period, Value					$ 30	$ 55
Payments to Acquire Businesses, Gross						$ 26.6
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends Payable, Date Declared			Oct. 25, 2018
Dividends declared, in dollars per share			$ 0.05
Dividends Payable, Date to be Paid	Nov. 20, 2018
Dividends Payable, Date of Record		Nov. 9, 2018
Scenario, Forecast [Member]
Subsequent Event [Line Items]
Business Exit Costs				$ 5
Payments to Acquire Businesses, Gross				$ 140

Quarterly Consolidated Financ_3

Quarterly Consolidated Financial Information (Unaudited) (Quarterly Financial Information Disclosure) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 254.3	$ 250.2	$ 233.2	$ 178.3	$ 226.9	$ 232.2	$ 199.7	$ 167.2	$ 916	$ 826	$ 800.6
Gross profit	85.5	74.5	74.5	55.4	81	82.6	52.5	51.8	289.9	267.9	268.9
Operating income	40.5	30.6	29.9	20.7	33.6	43	11.3	14.2	121.7	102.1	112.2
Income (Loss) from Continuing Operations, Net of Tax, Attributable to Parent	25	15.3	10.2	55.1	20.1	24.1	4.7	5.4	105.6	54.3	45.1
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent					(0.8)	(0.1)	68.6	1.3	0	69	18.8
Net Income (Loss) Attributable to Parent	$ 25	$ 15.3	$ 10.2	$ 55.1	$ 19.3	$ 24	$ 73.3	$ 6.7	$ 105.6	$ 123.3	$ 63.9
Net income (loss) per share(1)
Continuing operations	$ 0.16	$ 0.10	$ 0.06	$ 0.35	$ 0.13	$ 0.15	$ 0.03	$ 0.03	$ 0.67	$ 0.34	$ 0.28
Discontinued operations					(0.01)	0	0.43	0.01	0	0.43	0.12
Net income (loss) per basic share	0.16	0.10	0.06	0.35	0.12	0.15	0.46	0.04	0.67	0.77	0.40
Continuing operations	0.16	0.10	0.06	0.34	0.13	0.15	0.03	0.03	0.66	0.34	0.28
Income (Loss) from Discontinued Operations per share					(0.01)	0	0.42	0.01	0	0.42	0.11
Net income (loss) per diluted share	$ 0.16	$ 0.10	$ 0.06	$ 0.34	$ 0.12	$ 0.15	$ 0.45	$ 0.04	$ 0.66	$ 0.76	$ 0.39