Condensed Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating revenues:
Revenue from contract with customer excluding assessed tax	$ 5,132	$ 3,972	$ 9,781	$ 8,852
Total operating revenues	5,504	4,244	10,505	9,473
Operating expenses:
Compensation and benefits	1,022	905	2,048	1,964
Depreciation	550	551	1,099	1,098
Purchased services and materials	478	441	968	962
Fuel	497	247	908	681
Equipment and other rents	200	211	412	438
Other	284	235	604	533
Total operating expenses	3,031	2,590	6,039	5,676
Operating income	2,473	1,654	4,466	3,797
Other income (Note 6)	125	131	176	184
Interest expense	(282)	(289)	(572)	(567)
Income before income taxes	2,316	1,496	4,070	3,414
Income taxes	(518)	(364)	(931)	(808)
Net income	$ 1,798	$ 1,132	$ 3,139	$ 2,606
Share and Per Share (Note 8):
Earnings per share - basic	$ 2.73	$ 1.67	$ 4.73	$ 3.83
Earnings per share - diluted	$ 2.72	$ 1.67	$ 4.72	$ 3.82
Weighted average number of shares - basic	658.5	677.7	663.1	681.0
Weighted average number of shares - diluted	660.1	679.2	664.7	682.7
Cargo and Freight [Member]
Operating revenues:
Revenue from contract with customer excluding assessed tax	$ 5,132	$ 3,972	$ 9,781	$ 8,852
Other [Member]
Operating revenues:
Revenue from contract with customer excluding assessed tax	$ 372	$ 272	$ 724	$ 621