Debt (Tables)

6 Months Ended

Jun. 30, 2013

Debt Disclosure [Abstract]

Outstanding letters of credit under committed lines of credit

We had outstanding letters of credit under our committed lines of credit as follows (in millions):

				Amounts Outstanding
	Borrowing Capacity		Expiration	June 30, 2013		December 31, 2012
Letter of credit facilities	$	550	June 2014	$	250	$	418
Revolver	$	3,000	December 2016	$	59	$	59
Canadian revolving credit facility	C$	50	November 2013	C$	9	C$	10

Changes in accounts receivable sales facility

Changes in the amounts outstanding under our accounts receivable sales facility were as follows (in millions):

	Six Months Ended June 30,
	2013		2012
Balance as of beginning of period	$	100	$	250
Proceeds from the sale of receivables	—		1,300
Repayments	—		(1,450		)
Balance as of end of period	$	100	$	100