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Retirement Benefits (Schedule of Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Sep. 30, 2017 | Sep. 30, 2016 | Sep. 30, 2015
Defined Benefit Pension Plan [Member] |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at beginning of year | $ 232,949 | $ 208,101 |
Service cost | 2,808 | 2,444 | $ 2,802
Interest cost | 6,965 | 6,873 | 8,084
Net actuarial (gains) losses | (11,455) | 34,976 |
Contribution by participants | 69 | 67 |
Benefits paid | (7,911) | (12,445) |
Plan amendments | 3,694 | 0 |
Settlements | 0 | 47 |
Foreign currency exchange rate changes | 380 | (7,114) |
Projected benefit obligation at end of year | 227,499 | 232,949 | 208,101
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at beginning of year | 208,812 | 196,253 |
Actual return (loss) on plan assets | 22,609 | 30,061 |
Contributions by the Company | 671 | 999 |
Contributions by plan participants | 69 | 67 |
Benefits paid (plan assets) | (7,911) | (12,445) |
Settlements | 0 | (47) |
Foreign currency exchange rate changes | 462 | (6,076) |
Fair value of plan assets at end of year | 224,712 | 208,812 | 196,253
Net over/(under)funded status at end of year | (2,787) | (24,137) |
Defined Benefit Pension Plan [Member] | UNITED STATES |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at beginning of year | 160,892 | 145,870 |
Service cost | 1,675 | 1,695 | 2,018
Interest cost | 5,757 | 5,236 | 5,956
Net actuarial (gains) losses | (5,267) | 17,786 |
Contribution by participants | 55 | 47 |
Benefits paid | (5,676) | (9,789) |
Plan amendments | 3,694 | 0 |
Settlements | 0 | 47 |
Foreign currency exchange rate changes | 0 | 0 |
Projected benefit obligation at end of year | 161,130 | 160,892 | 145,870
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at beginning of year | 145,886 | 135,590 |
Actual return (loss) on plan assets | 20,067 | 19,859 |
Contributions by the Company | 0 | 226 |
Contributions by plan participants | 55 | 47 |
Benefits paid (plan assets) | (5,676) | (9,789) |
Settlements | 0 | (47) |
Foreign currency exchange rate changes | 0 | 0 |
Fair value of plan assets at end of year | 160,332 | 145,886 | 135,590
Net over/(under)funded status at end of year | (798) | (15,006) |
Defined Benefit Pension Plan [Member] | Foreign Plan [Member] |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at beginning of year | 72,057 | 62,231 |
Service cost | 1,133 | 749 | 784
Interest cost | 1,208 | 1,637 | 2,128
Net actuarial (gains) losses | (6,188) | 17,190 |
Contribution by participants | 14 | 20 |
Benefits paid | (2,235) | (2,656) |
Plan amendments | 0 | 0 |
Settlements | 0 | 0 |
Foreign currency exchange rate changes | 380 | (7,114) |
Projected benefit obligation at end of year | 66,369 | 72,057 | 62,231
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at beginning of year | 62,926 | 60,663 |
Actual return (loss) on plan assets | 2,542 | 10,202 |
Contributions by the Company | 671 | 773 |
Contributions by plan participants | 14 | 20 |
Benefits paid (plan assets) | (2,235) | (2,656) |
Settlements | 0 | 0 |
Foreign currency exchange rate changes | 462 | (6,076) |
Fair value of plan assets at end of year | 64,380 | 62,926 | 60,663
Net over/(under)funded status at end of year | (1,989) | (9,131) |
Defined Benefit Pension Plan [Member] | UNITED KINGDOM |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at end of year | 55,306 |  |
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at end of year | 52,810 |  |
Defined Benefit Pension Plan [Member] | JAPAN |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at end of year | 11,063 |  |
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at end of year | 11,570 |  |
Other Postretirement Benefit Plans [Member] |  |  |
Changes in projected benefit obligation: |  |  |
Projected benefit obligation at beginning of year | 35,630 | 34,927 |
Service cost | 14 | 22 | 30
Interest cost | 1,244 | 1,048 | 1,233
Net actuarial (gains) losses | (2,049) | 1,912 |
Contribution by participants | 1,365 | 1,299 |
Benefits paid | (3,964) | (3,503) |
Foreign currency exchange rate changes | 12 | (75) |
Projected benefit obligation at end of year | 32,252 | 35,630 | 34,927
Changes in fair value of plan assets: |  |  |
Fair value of plan assets at beginning of year | 0 | 0 |
Contributions by the Company | 2,599 | 2,204 |
Contributions by plan participants | 1,365 | 1,299 |
Benefits paid (plan assets) | (3,964) | (3,503) |
Fair value of plan assets at end of year | 0 | 0 | $ 0
Net over/(under)funded status at end of year | (32,252) | $ (35,630) |
Other Postretirement Benefit Plans [Member] | UNITED KINGDOM |  |  |
Changes in projected benefit obligation: |  |  |
Benefits paid | (21) |  |
Projected benefit obligation at end of year | $ 409 |  |

X
- Definition Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses. + 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)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive 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)(4) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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