Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

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	2018		2017		2018		2017		2018		2017		2018		2017
Operating revenue	$	3,744	$	3,471	$	3,831	$	3,599	$	3,613	$	3,615	$	3,580	$	3,629
Cost of revenue	2,181		2,003		2,231		2,087		2,096		2,092		2,096		2,124
Operating income	903		807		932		872		889		960		860		846
Net income (loss)	652		536		666		587		638		640		607		(76		)
Net income (loss) per share:
Basic	1.92		1.55		1.98		1.70		1.91		1.86		1.84		(0.22		)
Diluted	1.90		1.54		1.97		1.69		1.90		1.85		1.83		(0.22		)