Quarterly financial data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2015

Quarterly Financial Information Disclosure [Abstract]

Quarterly financial data (unaudited)

	2015 Quarters ended
(In millions, except per share data)	December 31		September  30		June 30		March 31
Product sales	$	5,329	$	5,516	$	5,225	$	4,874
Gross profit from product sales	4,258		4,482		4,136		3,841
Net income	1,800		1,863		1,653		1,623
Earnings per share:
Basic	$	2.39	$	2.46	$	2.18	$	2.13
Diluted	$	2.37	$	2.44	$	2.15	$	2.11
	2014 Quarters ended
(In millions, except per share data)	December  31		September  30		June 30		March 31
Product sales	$	5,174	$	4,848	$	4,949	$	4,356
Gross profit from product sales	3,991		3,780		3,868		3,266
Net income	1,294		1,244		1,547		1,073
Earnings per share:
Basic	$	1.70	$	1.63	$	2.04	$	1.42
Diluted	$	1.68	$	1.61	$	2.01	$	1.40