Quarterly Financial Information (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

Quarterly Financial Information (Unaudited) [Abstract]

Summarized quarterly financial data

			Consolidated Net Income After Dividends on	Per Common Share
	Operating Revenues	Operating Income	Preferred and Preference Stock	Basic Earnings		Trading Price Range
Quarter Ended			of Subsidiaries		Dividends	High	Low
	(in millions)
March 2011	$4,012	$   854	$422	$0.50	$0.4550	$38.79		$36.51
June 2011	4,521	1,136	604	0.71	0.4725	40.87		37.43
September 2011	5,428	1,652	916	1.07	0.4725	43.09		35.73
December 2011	3,696	589	261	0.30	0.4725	46.69		41.00
March 2010	$4,157	$   922	$495	$0.60	$0.4375	$33.73		$30.85
June 2010	4,208	951	510	0.62	0.4550	35.45		32.04
September 2010	5,320	1,459	817	0.98	0.4550	37.73		33.00
December 2010	3,771	470	153	0.18	0.4550	38.62		37.10