Derivative Instruments And Hedging Activities (Narrative) (Details) (USD $)	9 Months Ended
Sep. 30, 2011
(Proceeds from) or payments to settlement of interest rate protection agreement	$ (9,910,000)
Outstanding senior notes	400,000,000
Senior notes, maturity year	2013
Foreign currency forward contracts settled for a loss, amount	700,000
Number of foreign currency forward contracts outstanding	0
Fair Value of treasury locks	(41,700,000)
Notional amount of interest rate protection agreement outstanding	400,000,000
Interest rate contracts, expected year of maturity	2012
Amount of gain (loss) to be reclassified from accumulated OCI into income	1,800,000
Amount of gain (loss) to be reclassified from accumulated OCI into income, net of tax	1,200,000
Ineffective portion of derivative instruments	0
2003 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	(22,800,000)
2008 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	4,400,000
2010 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	$ (9,900,000)

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months, net of tax.

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- Definition

Expected year of maturity for interest rate contracts.

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- Definition

Amount of loss recorded in accumulated other comprehensive income pertaining to the settlement of foreign currency exchange rate derivatives designated as cash flow hedging instruments to the extent that a cash flow hedge is determined to be effective.

+ Details

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- Definition

Senior Notes Maturity Year

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- Definition

The estimated net amount of existing gains (losses) on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 45

-Subparagraph b(2)

+ Details

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- Definition

Amount of outstanding principal due under the debt instrument at the end of the reporting period.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number APB14-1

-Paragraph 31

-Subparagraph b

+ Details

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- Definition

The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph b

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- Definition

Fair value as of the balance sheet date of all interest rate derivative liabilities designated as cash flow hedging instruments.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 17

+ Details

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- Definition

Aggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.

+ Details

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- Definition

Number of foreign currency exchange rate derivatives held by the entity at the reporting date.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44

+ Details

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- Definition

The net cash outflow (inflow) for a financial contract that meets the hedge criteria as either cash flow hedge, fair value hedge or hedge of net investment in foreign operations.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 14

-Subparagraph FN4

+ Details

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