Debt (Schedule of Accounts Receivable Securitization Facility) (Details) - Accounts Receivable Securitization Facility [Member] - USD ($) $ in Millions		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Borrowings outstanding	[1]	$ 77	$ 80
Secured Debt [Member]
Debt Instrument [Line Items]
Borrowings outstanding	[2]	77
Letters of credit issued		29
Available for borrowing		5
Total borrowing base		111
Maximum borrowing base	[3]	120
Proceeds from Issuance of Debt		25
Repayments of Lines of Credit		28
Outstanding accounts receivable transferred by the Originators to the Transferor		$ 185

[1] The weighted average interest rate was 2.9% and 2.1% as of September 30, 2018 and December 31, 2017, respectively.

[2] The Company borrowed $25 million and repaid $28 million during the nine months ended September 30, 2018.

[3] Outstanding accounts receivable transferred to the SPE was $185 million.