Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data

	Three Months Ended
	March 31		June 30		September 30		December 31
	($ in millions, except per share amounts)
2015
Railway operating revenues	$	2,567	$	2,713	$	2,713	$	2,518
Income from railway operations	606		814		822		642
Net income	310		433		452		361
Earnings per share:
Basic	1.01		1.43		1.50		1.21
Diluted	1.00		1.41		1.49		1.20
2014
Railway operating revenues	$	2,689	$	3,042	$	3,023	$	2,870
Income from railway operations	667		1,019		998		891
Net income	368		562		559		511
Earnings per share:
Basic	1.18		1.81		1.80		1.65
Diluted	1.17		1.79		1.79		1.64