Selected Quarterly Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Selected Quarterly Data (Unaudited) [Abstract]

Selected Quarterly Data (Unaudited)

Millions, Except Per Share Amounts
2015	Mar. 31		Jun. 30		Sep. 30		Dec. 31
Operating revenues	$	5,614	$	5,429	$	5,562	$	5,208
Operating income		1,977		1,949		2,208		1,918
Net income		1,151		1,204		1,300		1,117
Net income per share:
Basic		1.31		1.38		1.51		1.31
Diluted		1.30		1.38		1.50		1.31

Millions, Except Per Share Amounts
2014	Mar. 31		Jun. 30		Sep. 30		Dec. 31
Operating revenues	$	5,638	$	6,015	$	6,182	$	6,153
Operating income		1,854		2,196		2,330		2,373
Net income		1,088		1,291		1,370		1,431
Net income per share:
Basic		1.20		1.43		1.53		1.62
Diluted		1.19		1.43		1.53		1.61