Face (par) amount of debt instrument at time of issuance.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=34725769&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28551-108399

+ Details

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Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

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Period Type:	duration

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Debt and Credit Agreements - Schedule of Notes Issued (Details) - Senior Notes - USD ($)	1 Months Ended
	Sep. 30, 2014	Dec. 31, 2010	Jul. 31, 2008	Jul. 31, 2001
7.33% weighted-average senior notes
Debt Instrument [Line Items]
Principal				$ 170,000,000
7.33% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal				$ 75,000,000
Term				10 years
Coupon (as a percent)				7.26%
7.33% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal				$ 75,000,000
Term				12 years
Coupon (as a percent)				7.36%
7.33% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal				$ 20,000,000
Term				15 years
Coupon (as a percent)				7.46%
6.51% weighted-average senior notes
Debt Instrument [Line Items]
Principal			$ 425,000,000
6.51% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal			$ 245,000,000
Term			10 years
Coupon (as a percent)			6.44%
6.51% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal			$ 100,000,000
Term			12 years
Coupon (as a percent)			6.54%
6.51% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal			$ 80,000,000
Term			15 years
Coupon (as a percent)			6.69%
5.58% weighted-average senior notes
Debt Instrument [Line Items]
Principal		$ 175,000,000
5.58% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal		$ 88,000,000
Term		10 years
Coupon (as a percent)		5.42%
5.58% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal		$ 25,000,000
Term		12 years
Coupon (as a percent)		5.59%
5.58% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal		$ 62,000,000
Term		15 years
Coupon (as a percent)		5.80%
3.65% weighted-average senior notes
Debt Instrument [Line Items]
Principal	$ 925,000,000
3.65% weighted-average senior notes \| Tranche 1
Debt Instrument [Line Items]
Principal	$ 100,000,000
Term	7 years
Coupon (as a percent)	3.24%
3.65% weighted-average senior notes \| Tranche 2
Debt Instrument [Line Items]
Principal	$ 575,000,000
Term	10 years
Coupon (as a percent)	3.67%
3.65% weighted-average senior notes \| Tranche 3
Debt Instrument [Line Items]
Principal	$ 250,000,000
Term	12 years
Coupon (as a percent)	3.77%