Represents the period over which first 50 percent unrecognized compensation is expected to be recognized for equity-based compensation plans, in PnYnMnDTnHnMnS format, for example, P1Y5M13D represents the reported fact of one year, five months, and thirteen days.

No definition available.

Equity Incentive Plan (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 28, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Equity Incentive Plan
Maximum number of common shares available for issuance (in shares)		6,828,527		6,828,527
Restricted share awards
Summary of non-vested shares/units
Unvested at the beginning of the period (in shares)				2,267,870
Granted (in shares)				991,453
Vested (in shares)				(905,666)
Forfeited (in shares)				(25,828)
Unvested at the end of the period (in shares)		2,327,829		2,327,829
Weighted Average Grant Date Fair Value
Unvested at the beginning of the period (in dollars per share)				$ 15.32
Granted (in dollars per share)				10.84
Vested (in dollars per share)				15.20
Forfeited (in dollars per share)				13.13
Unvested at the end of the period (in dollars per share)		$ 13.48		$ 13.48
Other Disclosures
Share-based compensation expense		$ 4.0	$ 3.5	$ 11.4	$ 10.7
Total unrecognized compensation costs		17.7		$ 17.7
Weighted-average period of recognition of unrecognized share-based compensation expense				1 year 6 months
Total fair value of shares vested				$ 9.7	8.8
2015 Share Repurchase Program [Member]
Other Disclosures
Performance-based vesting period				3 years
Time-based vesting period				1 year
Percentage of grant date fair value to be recognized over three years				50.00%
Employee service share based compensation cost period of recognition				3 years
Percentage of grant date fair value to be recognized over four years				50.00%
Employee service share based compensation cost period of recognition				4 years
Performance Units
Other Disclosures
Share-based compensation expense		2.3	$ 1.9	$ 6.7	$ 5.4
Total unrecognized compensation costs		$ 13.1		$ 13.1
Weighted-average period of recognition of unrecognized share-based compensation expense				1 year 10 months 24 days
Performance-based vesting period				4 years
2020 Performance Shares [Member]
Summary of non-vested shares/units
Granted (in shares)	200,000						489,000
Unvested at the end of the period (in shares)		100,000		100,000
Other Disclosures
Total fair value of shares vested				$ 1.1
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Intrinsic Value, Amount Per Share							$ 11.59
Fair value assumptions, risk free interest rate							1.08%
Fair value assumptions, expected volatility rate							23.46%
2021 Performance Shares
Summary of non-vested shares/units
Granted (in shares)						431,151
Other Disclosures
Performance-based vesting period				3 years
Percentage of grant date fair value to be recognized over three years				100.00%
Employee service share based compensation cost period of recognition				3 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Contingent on Absolute Total Shareholder Return				25.00%
Share-Based Compensation Arrangement by Share-Based Payment Award, Contingent on Relative Total Shareholder Return				75.00%
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Intrinsic Value, Amount Per Share						$ 20.90
Fair value assumptions, risk free interest rate						0.23%
Fair value assumptions, expected volatility rate						69.47%
2022 Performance Shares
Summary of non-vested shares/units
Granted (in shares)					407,024
Other Disclosures
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Intrinsic Value, Amount Per Share					$ 21.96
Fair value assumptions, risk free interest rate					1.70%
Fair value assumptions, expected volatility rate					70.15%
2021 Share Repurchase Program
Other Disclosures
Common shares available for future grant (in shares)		2,688,397		2,688,397
2023 Performance Shares
Summary of non-vested shares/units
Granted (in shares)				574,846
Other Disclosures
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Intrinsic Value, Amount Per Share				$ 16.90
Fair value assumptions, risk free interest rate				4.33%
Fair value assumptions, expected volatility rate				66.70%
Minimum \| 2020 Performance Shares [Member]
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range						0.00%
Minimum \| 2021 Performance Shares
Other Disclosures
Percentage of performance units that will convert into restricted shares				0.00%
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range					0.00%
Minimum \| 2022 Performance Shares
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range				0.00%
Minimum \| 2023 Performance Shares
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range				0.00%
Maximum \| 2020 Performance Shares [Member]
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range						200.00%
Maximum \| 2021 Performance Shares
Other Disclosures
Percentage of performance units that will convert into restricted shares				200.00%
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range					200.00%
Maximum \| 2022 Performance Shares
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range				200.00%
Maximum \| 2023 Performance Shares
Other Disclosures
Shared-Based Compensation Arrangement by Share-Based Payment Award, Conversion Percentage Range				200.00%