Supplementary Quarterly Financial Information (Unaudited ) (Tables)

12 Months Ended

Dec. 31, 2012

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information [Table Text Block]

	First Quarter		Second Quarter		Third Quarter		Fourth Quarter
									Year
2012	(In millions)
Operating Revenues	$	1,198	$	1,289	$	1,542	$	1,262	$	5,291
Operating Income (a)	213		265		378		172		1,028
Net Income	97		127		195		67		486
2011
Operating Revenues	1,192		1,240		1,517		1,203		5,152
Operating Income	205		235		335		227		1,002
Net Income	85		104		158		90		437