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Stock-based Compensation Plans (Narrative) (Details) $ / shares in Units, $ in Millions |  |  | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | ---
Jan. 27, 2021 | Dec. 02, 2020 | Jun. 30, 2021 USD ($) $ / shares shares | Mar. 31, 2021 $ / shares shares | Dec. 31, 2020 $ / shares shares | Jun. 30, 2020 USD ($) shares | Jun. 30, 2021 USD ($) $ / shares shares | Jun. 30, 2020 USD ($) shares
Share-based Payment Arrangement, Expense | $ |  |  | $ 3.4 |  |  | $ 1.8 | $ 8.4 | $ 5.0
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ |  |  | $ 11.5 |  |  |  | $ 11.5 |
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount |  |  | 131,178 |  |  | 474,423 | 566,666 | 274,009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares |  |  | 0 |  |  |  | 108,950 |
Phantom Share Units (PSUs) [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instrument Other than Option, Nonvested, Intrinsic Value | $ / shares |  |  | $ 14.42 |  |  |  | $ 14.42 |
Share-based compensation liability | $ |  |  | $ 2.7 |  |  |  | $ 2.7 |
Granted, shares |  |  | 3,567 | 1,254 | 180,987 |  |  |
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, Weighted Average Grant Date Fair Value | $ / shares |  |  | $ 14.29 | $ 11.94 | $ 11.86 |  |  |
Granted, shares |  |  | 3,567 | 1,254 | 180,987 |  |  |
Performance Shares [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  |  |  |  |  | 103,058 |
Share-based compensation, units awarded but not yet granted |  |  | 199,994 |  |  |  | 199,994 |
Restricted Stock Units (RSUs) [Member] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period |  |  | 2,324 |  |  |  | 221,873 |
Granted, shares |  |  | 7,127 | 82,565 | 129,081 |  |  |
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, Weighted Average Grant Date Fair Value | $ / shares |  |  | $ 13.32 | $ 12.81 | $ 11.86 |  |  |
Granted, shares |  |  | 7,127 | 82,565 | 129,081 |  |  |
Market Based Performance Shares |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | 1.84% | 1.77% |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate | 0.16% | 0.21% |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | 2 years 8 months 1 day | 2 years 9 months 29 days |  |  |  |  |  |
Granted, shares |  |  |  | 4,187 | 234,199 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate | 1.84% | 1.77% |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  | $ 14.26 | $ 15.39 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate | 0.16% | 0.21% |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term | 2 years 8 months 1 day | 2 years 9 months 29 days |  |  |  |  |  |
Granted, shares |  |  |  | 4,187 | 234,199 |  |  |
Equity Option |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |  |  | 2.01% | 2.01% |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate |  |  | 0.66% | 0.66% |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term |  |  | 6 years | 6 years |  |  |  |
Granted, shares |  |  |  | 8,115 | 423,405 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate |  |  | 2.01% | 2.01% |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value | $ / shares |  |  |  | $ 3.08 | $ 3.05 |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate |  |  | 0.66% | 0.66% |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term |  |  | 6 years | 6 years |  |  |  |
Granted, shares |  |  |  | 8,115 | 423,405 |  |  |
Minimum [Member] | Performance Shares [Member] |  |  |  |  |  |  |  |
Performance Factors |  |  |  |  |  |  | 0 |
Minimum [Member] | Market Based Performance Shares |  |  |  |  |  |  |  |
Performance Factors |  |  |  |  |  |  | 0 |
Maximum [Member] | Performance Shares [Member] |  |  |  |  |  |  |  |
Performance Factors |  |  |  |  |  |  | 2 |
Maximum [Member] | Market Based Performance Shares |  |  |  |  |  |  |  |
Performance Factors |  |  |  |  |  |  | 2 |
Share-based Payment Arrangement, Tranche Two [Member] | Performance Shares [Member] |  |  |  |  |  |  |  |
Granted, shares |  |  |  |  | 60,019 |  |  |
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, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  | $ 11.86 |  |  |
Granted, shares |  |  |  |  | 60,019 |  |  |
Share-based Payment Arrangement, Tranche Three [Member] | Performance Shares [Member] |  |  |  |  |  |  |  |
Granted, shares |  |  |  |  | 84,483 |  |  |
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, Weighted Average Grant Date Fair Value | $ / shares |  |  |  |  | $ 11.86 |  |  |
Granted, shares |  |  |  |  | 84,483 |  |  |

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