v2.4.1.9
Summary Of Significant Accounting Policies (Schedule Of Allowance For Uncollectible Accounts) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Accounting Policies [Abstract]      
Allowances, beginning of year $ 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts $ 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts $ 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts
Amounts charged to expense 8us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsProvisionChargedToExpense1 3us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsProvisionChargedToExpense1 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsProvisionChargedToExpense1
Write-offs of uncollectible receivables (4)us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsWriteOffsAgainstAllowance (3)us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsWriteOffsAgainstAllowance (1)us-gaap_PremiumsReceivableAllowanceForDoubtfulAccountsWriteOffsAgainstAllowance
Allowances, end of year $ 5us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts $ 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts $ 1us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts