Senior Unsecured Notes (Summary Of Senior Unsecured Notes) (Details) (USD $)
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9 Months Ended | ||||||||||||
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Sep. 30, 2012
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May 25, 2012
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Dec. 31, 2011
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | $ 1,198,314,000 | $ 1,119,267,000 | |||||||||||
Loss from early extinguishment of debt | 4,415,000 | ||||||||||||
5.250% Senior Unsecured Notes, Due January 15, 2012 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 99,988,000 | [1] | |||||||||||
Effective Rate | 5.457% | [1],[2] | |||||||||||
Interest rate of Senior Unsecured Notes | 5.25% | [1] | |||||||||||
Maturity date of the Senior Unsecured Notes | Jan. 15, 2012 | [1] | |||||||||||
6.150% Senior Unsecured Notes, Due December 15, 2012 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 94,438,000 | [3] | |||||||||||
Effective Rate | 6.894% | [2],[3] | |||||||||||
Interest rate of Senior Unsecured Notes | 6.15% | [3] | |||||||||||
Maturity date of the Senior Unsecured Notes | Dec. 15, 2012 | [3] | |||||||||||
Principal amount of Senior Unsecured Notes redeemed | 94,900,000 | ||||||||||||
Redemption price as percentage of principal | 103.19% | ||||||||||||
Redemption price of Senior Unsecured Notes | 100,500,000 | ||||||||||||
Loss from early extinguishment of debt | 3,300,000 | ||||||||||||
5.820% Senior Unsecured Notes, Due March 15, 2013 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 25,972,000 | [4] | |||||||||||
Effective Rate | 6.448% | [2],[4] | |||||||||||
Interest rate of Senior Unsecured Notes | 5.82% | [4] | |||||||||||
Maturity date of the Senior Unsecured Notes | Mar. 15, 2013 | [4] | |||||||||||
Principal amount of Senior Unsecured Notes redeemed | 26,100,000 | ||||||||||||
Redemption price as percentage of principal | 103.87% | ||||||||||||
Redemption price of Senior Unsecured Notes | 27,400,000 | ||||||||||||
Loss from early extinguishment of debt | 1,100,000 | ||||||||||||
4.600% Senior Unsecured Notes, Due June 15, 2013 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 99,980,000 | 99,958,000 | |||||||||||
Effective Rate | 4.742% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 4.60% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Jun. 15, 2013 | ||||||||||||
5.125% Senior Unsecured Notes, Due February 15, 2014 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 200,330,000 | 200,509,000 | |||||||||||
Effective Rate | 5.11% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 5.125% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Feb. 15, 2014 | ||||||||||||
5.125% Senior Unsecured Notes, Due January 15, 2015 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 149,786,000 | 149,717,000 | |||||||||||
Effective Rate | 5.297% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 5.125% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Jan. 15, 2015 | ||||||||||||
5.800% Senior Unsecured Notes, Due January 15, 2016 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 200,256,000 | 200,313,000 | |||||||||||
Effective Rate | 5.806% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 5.80% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Jan. 15, 2016 | ||||||||||||
7.750% Senior Unsecured Notes, Due August 15, 2019 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | 248,532,000 | 248,372,000 | |||||||||||
Effective Rate | 8.017% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 7.75% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Aug. 15, 2019 | ||||||||||||
4.500% Senior Unsecured Notes Due April 18, 2022 [Member]
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Long-Term Debt [Line Items] | |||||||||||||
Senior Unsecured Notes | $ 299,430,000 | ||||||||||||
Effective Rate | 4.612% | [2] | |||||||||||
Interest rate of Senior Unsecured Notes | 4.50% | ||||||||||||
Maturity date of the Senior Unsecured Notes | Apr. 18, 2022 | ||||||||||||
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