Stockholders' Equity - Changes in Stockholders' Equity (Details) (USD $) Share data in Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014 Number of Common shares Issued [Member]	Sep. 30, 2013 Number of Common shares Issued [Member]	Sep. 30, 2014 Number of Common shares Treasury [Member]	Sep. 30, 2013 Number of Common shares Treasury [Member]	Sep. 30, 2014 Common Stockholders' Equity [Member]	Sep. 30, 2013 Common Stockholders' Equity [Member]	Sep. 30, 2013 Preferred and Preference Stock of Subsidiaries [Member]	Sep. 30, 2014 Preferred and Preference Stock of Subsidiaries [Member]	Dec. 31, 2013 Preferred and Preference Stock of Subsidiaries [Member]
Changes in Stockholders' Equity
Beginning Balance					$ 19,764,000,000		$ 19,004,000,000						$ 19,008,000,000	$ 18,297,000,000	$ 707,000,000	$ 756,000,000	$ 756,000,000
Beginning Balance, Shares									892,733	877,803	5,647	10,035
Net income after dividends on preferred and preference stock	718,000,000	[1],[2]	852,000,000	[1],[2]	1,680,000,000	[1],[3]	1,230,000,000	[1],[3]					1,680,000,000	1,230,000,000
Other comprehensive income (loss)					6,000,000		11,000,000						6,000,000	11,000,000
Treasury stock re-issued, Shares											4,996	1,956
Treasury stock re-issued					225,000,000		89,000,000						225,000,000	89,000,000
Stock issued, Shares									7,781	12,046
Stock issued					332,000,000		533,000,000						332,000,000	484,000,000	49,000,000
Stock repurchased, at cost					(5,000,000)		(19,000,000)						(5,000,000)	(19,000,000)
Cash dividends on common stock					(1,390,000,000)		(1,314,000,000)						(1,390,000,000)	(1,314,000,000)
Other, Shares											(51)	(30)
Other					1,000,000		0						1,000,000	0
Ending Balance	$ 20,613,000,000		$ 19,534,000,000		$ 20,613,000,000		$ 19,534,000,000						$ 19,857,000,000	$ 18,778,000,000	$ 756,000,000	$ 756,000,000	$ 756,000,000
Ending Balance, Shares									900,514	889,849	702	8,109

[1] After dividends on preferred and preference stock of subsidiaries.

[2] Segment net income (loss) for the traditional operating companies for the three months ended September 30, 2014 and September 30, 2013 includes a $418.0 million pre-tax charge ($258.1 million after tax) and a $150.0 million pre-tax charge ($92.6 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein for additional information.

[3] Segment net income (loss) for the traditional operating companies for the nine months ended September 30, 2014 and September 30, 2013 includes $798.0 million in pre-tax charges ($492.8 million after tax) and $1.14 billion in pre-tax charges ($704.0 million after tax), respectively, for estimated probable losses on the Kemper IGCC. See Note (B) under "Integrated Coal Gasification Combined Cycle – Kemper IGCC Schedule and Cost Estimate" herein for additional information.