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Senior Unsecured Notes (Narrative) (Details) (USD $)
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6 Months Ended | |
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Jun. 30, 2013
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Jun. 30, 2012
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| Debt Instrument [Line Items] | ||
| Proceeds from the sale of senior unsecured notes | $ 268,928,000 | $ 299,403,000 |
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3.150% Senior Unsecured Note, Due May 15, 2023 [Member]
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| Debt Instrument [Line Items] | ||
| Face amount of senior unsecured notes | 275,000,000 | |
| Interest rate of Senior Unsecured Notes | 3.15% | |
| Maturity date of the Senior Unsecured Notes | May 15, 2023 | |
| Proceeds from the sale of senior unsecured notes | $ 266,500,000 | |
| X | ||||||||||
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- Definition
The stated principal amount of the debt instrument at time of issuance, which may vary from the carrying amount because of unamortized premium or discount. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Interest rate stated in the contractual debt agreement. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Details
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- Definition
Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
The cash inflow from the issuance of long-term debt that is not secured by collateral. Excludes proceeds from tax exempt unsecured debt. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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