Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

Quarterly Financial Information Disclosure [Abstract]

Schedule of quarterly financial data

	2011
(in millions, except per-share amounts)	Total			Fourth			Third		Second			First
Operating revenue	$	12,760		$	3,013		$	3,981	$	2,983		$	2,782
Operating income (loss)	320			(1,319		)	810		380			450
Income (loss) from continuing operations	24			(824		)	441		192			216
Income (loss) from discontinued operations – net	(3		)	—			—		(1		)	(2		)
Net income (loss) attributable to common shareholders	(37		)	(839		)	426		176			200
Basic earnings (loss) per share:
Continuing operations	(0.10		)	(2.57		)	1.31		0.54			0.62
Discontinued operations	(0.01		)	—			—		—			(0.01		)
Total	(0.11		)	(2.57		)	1.31		0.54			0.61
Diluted earnings (loss) per share1:
Continuing operations	(0.10		)	(2.57		)	1.30		0.54			0.62
Discontinued operations	(0.01		)	—			—		—			(0.01		)
Total	(0.11		)	(2.57		)	1.30		0.54			0.61
Dividends declared per share	1.285			0.325			0.320		0.320			0.320
Common stock prices:
High	41.57			41.57			39.25		40.15			39.20
Low	32.64			35.63			32.64		36.54			35.12
Close	41.40			41.40			38.25		38.75			36.59

	2010
(in millions, except per-share amounts)	Total		Fourth		Third			Second		First
Operating revenue	$	12,409	$	3,069	$	3,788		$	2,741	$	2,810
Operating income	2,126		414		862			351		498
Income from continuing operations	1,303		178		527			356		243
Income (loss) from discontinued operations – net	4		—		(4		)	1		6
Net income attributable to common shareholders	1,256		166		510			344		236
Basic earnings (loss) per share:
Continuing operations	3.83		0.51		1.57			1.05		0.70
Discontinued operations	0.01		—		(0.01		)	—		0.02
Total	3.84		0.51		1.56			1.05		0.72
Diluted earnings (loss) per share:
Continuing operations	3.81		0.51		1.57			1.05		0.70
Discontinued operations	0.01		—		(0.01		)	—		0.02
Total	3.82		0.51		1.56			1.05		0.72
Dividends declared per share	1.265		0.320		0.315			0.315		0.315
Common stock prices:
High	39.37		39.37		35.15			34.74		35.82
Low	30.37		34.38		31.06			30.37		31.88
Close	38.60		38.60		34.39			31.72		34.17

¹  Due to a loss for the three months and year ended December 31, 2011, there are no incremental shares in the diluted computation because such shares would be considered antidilutive.