Long-Term Debt (Credit Facility End of Period Disclosures Narrative) (Details) (USD $)	9 Months Ended
Sep. 30, 2012
Credit Facility, Name [Member] \| Credit Facility, Type of Debt [Member]
Debt Instrument [Line Items]
Minimum Number of Additional Tranches Available in Future	1
Aggregate Principal Amount of Each Tranche Available in Future	$ 1,000,000,000
Debt, Weighted Average Interest Rate	4.10%
Credit Facility, Revolving Credit Loans [Member] \| Line of Credit [Member]
Debt Instrument [Line Items]
Letters of Credit Outstanding, Amount	$ 37,700,000

Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of debt outstanding by type or by instrument at that time.

No definition available.

Name:	us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant