Interim Pension and Other Postretirement Benefits (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits [Member]
Components of net periodic pension cost [Abstract]
Service Cost	$ 5,216	$ 4,698	$ 15,649	$ 14,093
Interest Cost	6,296	7,095	18,890	21,284
Expected return on assets	(6,993)	(6,881)	(20,981)	(20,642)
Amortization of transition (asset)/obligation	0	0	0	0
Amortization of prior service (credit)/cost	(57)	(57)	(173)	(170)
Amortization of actuarial (gain) loss	4,248	3,319	12,746	9,959
Net periodic pension cost	$ 8,710	$ 8,174	$ 26,131	$ 24,524
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount Rate	3.73%	4.55%	3.73%	4.55%
Rate of compensation increase	3.50%	3.50%	3.50%	3.50%
Expected return on plan assets	7.00%	7.00%	7.00%	7.00%
Current Year Benefit Plan Contributions [Abstract]
Contributions Actual			$ 5,000
Other Benefits [Member]
Components of net periodic pension cost [Abstract]
Service Cost	$ 3,109	$ 2,705	9,327	$ 8,117
Interest Cost	2,669	3,106	8,009	9,318
Expected return on assets	(1,796)	(1,566)	(5,389)	(4,698)
Amortization of transition (asset)/obligation	0	21	0	62
Amortization of prior service (credit)/cost	(411)	(411)	(1,233)	(1,233)
Amortization of actuarial (gain) loss	(706)	(541)	(2,120)	(1,625)
Net periodic pension cost	$ 2,865	$ 3,314	$ 8,594	$ 9,941
Defined Benefit Plan Weighted Average Assumptions Used In Calculating Net Periodic Benefit Cost Abstract
Discount Rate	3.73%	4.55%	3.73%	4.55%
Expected return on plan assets	4.45%	4.45%	4.45%	4.45%
Current Year Benefit Plan Contributions [Abstract]
Contributions Actual			$ 9,900
Other Benefits [Member] \| Minimum [Member]
Current Year Benefit Plan Contributions [Abstract]
Defined Benefit Plan, Expected Contributions in Current Fiscal Year			10,000
Other Benefits [Member] \| Maximum [Member]
Current Year Benefit Plan Contributions [Abstract]
Defined Benefit Plan, Expected Contributions in Current Fiscal Year			$ 20,000

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

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The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

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The amount of the transition obligation or asset recognized in net periodic benefit cost.

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The interest rate used to adjust for the time value of money.

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

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- Definition

Expected rate of compensation increases (for pay-related plans).

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- Definition

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

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

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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
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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.

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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.

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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
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