Condensed Consolidated Statements of Financial Position (Unaudited) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets [Abstract]
Cash and cash equivalents	$ 1,537	$ 1,432
Accounts receivable, net (Note 11)	1,666	1,414
Materials and supplies	739	653
Current deferred income taxes	239	268
Other current assets	322	223
Total current assets	4,503	3,990
Investments	1,369	1,321
Net properties (Note 12)	44,901	43,749
Other assets	789	671
Total assets	51,562	49,731
Current liabilities [Abstract]
Accounts payable and other current liabilities (Note 13)	3,319	3,086
Debt due within one year (Note 15)	458	705
Total current liabilities	3,777	3,791
Debt due after one year (Note 15)	10,385	8,872
Deferred income taxes	14,301	14,163
Other long-term liabilities	1,659	1,680
Commitments and contingencies (Note 17)
Total liabilities	30,122	28,506
Common shareholders' equity (Note 4) [Abstract]
Common shares, $2.50 par value, 1,400,000,000 authorized; 1,110,115,474 and 1,109,657,652 issued; 899,019,384 and 912,001,996 outstanding, respectively	2,775	2,774
Paid-in-surplus	4,269	4,210
Retained earnings	25,456	23,901
Treasury stock	(10,346)	(8,910)
Accumulated other comprehensive loss (Note 10)	(714)	(750)
Total common shareholders' equity	21,440	21,225
Total liabilities and common shareholders' equity	$ 51,562	$ 49,731