Benefit Plans - Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Nov. 30, 2014	Nov. 30, 2013
Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	$ 9,058	$ 7,467
Interest costs	7,014	6,698
Expected return on assets	(12,438)	(12,734)
Prior service cost (credit) amortization	407	399
Actuarial loss (gain) amortization	4,901	4,644
Transition amount amortization	0	0
Periodic benefit costs, net	8,942	6,474
Defined Benefit Plan, Contributions by Employer	0
Non-Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	225	179
Interest costs	352	336
Expected return on assets	0	0
Prior service cost (credit) amortization	57	57
Actuarial loss (gain) amortization	261	227
Transition amount amortization	0	0
Periodic benefit costs, net	895	799
Other Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	472	482
Interest costs	415	519
Expected return on assets	0	0
Prior service cost (credit) amortization	(30)	(30)
Actuarial loss (gain) amortization	(105)	0
Transition amount amortization	0	124
Periodic benefit costs, net	$ 752	$ 1,095

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

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- Definition

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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- Definition

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

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- Definition

The increase in the fair value of plan assets from contributions made by the employer.

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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

-Topic 715

-SubTopic 30

-Glossary Expected Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512136

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 60

-Glossary Expected Return on Plan Assets

-URI http://asc.fasb.org/extlink&oid=6512171

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(3)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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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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- 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.

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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

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (h)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

Reference 2: 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

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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