Retirement Benefits - Narrative (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | |||
|---|---|---|---|---|---|
Mar. 31, 2018 |
Dec. 31, 2017 |
Mar. 31, 2017 |
Mar. 31, 2018 |
Mar. 31, 2017 |
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| Retirement Benefits [Abstract] | |||||
| Pension Contributions | $ 80.0 | ||||
| Postemployment Benefits, Period Expense | $ 0.1 | $ 0.1 | $ 0.1 | $ 0.2 | |
| Defined Contribution Plan, Cost | $ 2.9 | $ 3.1 | $ 5.6 | $ 5.7 | |
| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of contribution received by defined benefit plan from employer which increases plan assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Amount of cost for defined contribution plan. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Period expense related to postemployment benefits. No definition available.
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