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Retirement Plans (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Defined Benefit Plan, Fair Value of Plan Assets | $ 36.4 | $ 33.7 |
Defined Benefit Plan, Benefit Obligation | $ 36.5 | $ 38.5 |
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | 3.80% | 3.60% |
Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation | $ 0.1 | $ 4.8 |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) | $ 0.3 | 0.2 | $ 0.1
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | 6.00% |  |
Defined Benefit Plan, Plan Assets, Contributions by Employer | $ 2.0 | 1.8 |
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year | 2.1 |  |
Defined Benefit Plan, Expected Future Benefit Payment, Year Two | 2.1 |  |
Defined Benefit Plan, Expected Future Benefit Payment, Year Three | 2.0 |  |
Defined Benefit Plan, Expected Future Benefit Payment, Year Four | 2.0 |  |
Defined Benefit Plan, Expected Future Benefit Payment, Year Five | 1.9 |  |
Defined Benefit Plan, Expected Future Benefit Payment, Five Fiscal Years Thereafter | 9.5 |  |
Defined Contribution Plan, Employer Discretionary Contribution Amount | $ 6.1 | $ 5.3 | $ 5.1
Debt Securities [Member] |  |  |
Defined Benefit Plan, Actual Plan Asset Allocations | 80.00% |  |
Equity Securities [Member] |  |  |
Defined Benefit Plan, Actual Plan Asset Allocations | 20.00% |  |
UK Plan [Member] |  |  |
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage | 100.00% |  |
UK Plan [Member] | Maximum [Member] |  |  |
Defined Contribution Plan, Employer Matching Contribution, Percent | 10.00% |  |
401k Plan [Member] |  |  |
Defined Contribution Plan, Employer Matching Contribution, Percent | 62.50% |  |
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage | 8.00% |  |
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage, Two to Three Years | 33.00% |  |
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage, Three to Four Years | 66.00% |  |
Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage, All Years | 100.00% |  |
401k Plan [Member] | Maximum [Member] |  |  |
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent | 80.00% |  |
401k Plan [Member] | Minimum [Member] |  |  |
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent | 1.00% |  |

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- Definition Defined Contribution Plan, Employers Matching Contribution, Annual Vesting Percentage, Two to Three Years + References No definition available. + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (k)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of benefits for defined benefit plan expected to be paid in next fiscal year following latest fiscal year. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Fair value of assets that have been segregated and restricted to provide pension or postretirement benefits. Assets include, but are not limited to, stocks, bonds, other investments, earnings from investments, and contributions by the employer and employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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