Long-Term Debt (Percentages Per Annum) (Details)	12 Months Ended
Dec. 31, 2014
Standard & Poor's, BBB Rating \| Moody's, Baa1 Rating
Line of Credit Facility [Line Items]
Debt Ratings	BBB+/Baa1
Applicable Rate Commitment Fee	0.125%
Base Rate	0.125%
Standard & Poor's, BBB Rating \| Moody's, Baa1 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.125%
Standard & Poor's, BBB Rating \| Moody's, Baa2 Rating
Line of Credit Facility [Line Items]
Debt Ratings	BBB/Baa2
Applicable Rate Commitment Fee	0.175%
Base Rate	0.25%
Standard & Poor's, BBB Rating \| Moody's, Baa2 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.25%
Standard & Poor's, BBB- \| Moody's, Baa3 Rating
Line of Credit Facility [Line Items]
Debt Ratings	BBB-/Baa3
Applicable Rate Commitment Fee	0.225%
Base Rate	0.50%
Standard & Poor's, BBB- \| Moody's, Baa3 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.50%
Standard & Poor's, BB \| Moody's, Ba1 Rating
Line of Credit Facility [Line Items]
Debt Ratings	BB+/Ba1
Applicable Rate Commitment Fee	0.275%
Base Rate	0.625%
Standard & Poor's, BB \| Moody's, Ba1 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.625%
Minimum \| Standard & Poor's, A- Rating \| Moody's, A3 Rating
Line of Credit Facility [Line Items]
Debt Ratings	A-/A3 or better
Applicable Rate Commitment Fee	0.10%
Base Rate	0.00%
Minimum \| Standard & Poor's, A- Rating \| Moody's, A3 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.00%
Maximum \| Standard & Poor's, BB Rating \| Moody's, Ba2 Rating
Line of Credit Facility [Line Items]
Debt Ratings	BB/Ba2 or worse
Applicable Rate Commitment Fee	0.35%
Base Rate	0.75%
Maximum \| Standard & Poor's, BB Rating \| Moody's, Ba2 Rating \| Eurodollar
Line of Credit Facility [Line Items]
EuroDollar Rate/Letter of Credit	1.75%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

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- Definition

Description of the credit rating indicative of likelihood of repayment of the debt instrument given by a credit rating agency (for example, Standard and Poor's, Moody's, Fitch).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

+ Details

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- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

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- Definition

The effective interest rate during the reporting period.

+ 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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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