Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

	Three Months Ended
	March 31				June 30				September 30				December 31
In millions except per share amounts	2017		2016		2017		2016		2017		2016		2017			2016
Operating revenue	$	3,471	$	3,274	$	3,599	$	3,431	$	3,615	$	3,495	$	3,629		$	3,399
Cost of revenue	2,004		1,896		2,087		1,967		2,094		2,027		2,124			2,006
Operating income	809		722		874		792		961		808		850			742
Net income	536		468		587		525		640		535		(76		)	507
Net income (loss) per share:
Basic	1.55		1.29		1.70		1.47		1.86		1.51		(0.22		)	1.46
Diluted	1.54		1.29		1.69		1.46		1.85		1.50		(0.22		)	1.45