Benefit Plans - Net Periodic Benefit Cost (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Feb. 28, 2014	Feb. 28, 2013	Feb. 28, 2014	Feb. 28, 2013
Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	$ 7,802	$ 7,216	$ 15,269	$ 14,432
Interest costs	8,240	6,501	14,938	13,006
Expected return on assets	(11,082)	(11,967)	(23,816)	(23,923)
Prior service cost (credit) amortization	398	400	797	799
Actuarial loss (gain) amortization	4,445	5,230	9,089	10,461
Transition amount amortization
Periodic benefit costs, net	9,803	7,380	16,277	14,775
Defined Benefit Plan, Contributions by Employer			0
Non-Qualified Pension Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	248	164	427	329
Interest costs	486	324	822	647
Expected return on assets
Prior service cost (credit) amortization	57	57	114	114
Actuarial loss (gain) amortization	241	211	468	422
Transition amount amortization
Periodic benefit costs, net	1,032	756	1,831	1,512
Other Benefits
Component of net periodic benefit costs: [Abstract]
Service costs	476	634	958	1,267
Interest costs	502	616	1,021	1,232
Expected return on assets
Prior service cost (credit) amortization	(30)	(5)	(60)	(9)
Actuarial loss (gain) amortization	(187)	223	(187)	446
Transition amount amortization	(124)	174		349
Periodic benefit costs, net	$ 637	$ 1,642	$ 1,732	$ 3,285

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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+ Details

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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=28361610&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=28361610&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=28361610&loc=d3e1928-114920

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