Debt (Schedule of Accounts Receivable Securitization Facility)(Details) - Accounts Receivable Securitization Facility [Member] - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Borrowings outstanding	[1]	$ 81	$ 0
Secured Debt [Member]
Debt Instrument [Line Items]
Borrowings outstanding	[2]	81
Letters of credit issued		31
Available for borrowing		7
Total borrowing base		119
Maximum borrowing base	[3]	120
Proceeds from Issuance of Debt		85
Repayments of Lines of Credit		4
Outstanding accounts receivable transferred by the Originators to the Transferor		$ 153

[1] The weighted average interest rate was 2.0% as of September 30, 2017.

[2] The Company borrowed $85 million and repaid $4 million under its Accounts Receivable Securitization Facility during the nine months ended September 30, 2017.

[3] Outstanding accounts receivable transferred to the SPE was $153 million.