Pension and Post-retirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Defined Benefit Pension Plans
Pension Plan and Retirement Benefits
Service cost	$ 1,571	$ 1,020	$ 4,712	$ 3,060
Interest cost	2,712	2,549	7,853	8,262
Expected return	(3,699)	(2,978)	(10,702)	(9,753)
Amortizations	3,029	2,320	9,004	7,086
Net periodic cost	3,613	2,911	10,867	8,655
U.S. pension plan
Pension Plan and Retirement Benefits
Contribution to plan			4,500
Expected future employer contribution			1,500
U.K. pension plan
Pension Plan and Retirement Benefits
Contribution to plan			586
Expected future employer contribution			192
Postretirement Health Care Benefits
Pension Plan and Retirement Benefits
Service cost	87	58	261	174
Interest cost	1,073	1,149	3,219	3,447
Amortizations	1,070	706	3,210	2,118
Net periodic cost	$ 2,230	$ 1,913	6,690	$ 5,739
Contribution to plan			3,411
Expected future employer contribution			$ 1,589

The amount of gains or losses recognized in net periodic benefit cost.

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- Definition

Amount of contributions made by the employer to defined benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
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+ References

No definition available.

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- Definition

An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512171

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-Publisher FASB
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- Definition

The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

+ References

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- Definition

The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

+ References

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- Definition

The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Service Cost (Component of Net Periodic Pension Cost)
-URI http://asc.fasb.org/extlink&oid=6525008

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-Name Accounting Standards Codification
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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan in the current remaining fiscal period.

+ References

No definition available.

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