Fair value measurements (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of fair value, assets and liabilities measured on recurring basis

The following table summarizes the types of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in millions):



	December 31, 2018								December 31, 2017
	Level 1		Level 2		Level 3		Total		Level 1		Level 2		Level 3		Total
Assets:
Available-for-sale debt securities:
U.S. treasury securities	$	3,969	$	—	$	—	$	3,969	$	4,061	$	—	$	—	$	4,061
Certificates of deposit	—		4,361		—		4,361		—		5,131		—		5,131
U.S. government agencies securities	—		938		—		938		—		926		—		926
Non-U.S. government securities	—		305		—		305		—		664		—		664
Corporate debt securities	—		13,067		—		13,067		—		14,747		—		14,747
Residential mortgage and asset-backed securities	—		1,524		—		1,524		—		4,058		—		4,058
Marketable equity securities:
Money market funds	5,305		—		—		5,305		4,714		—		—		4,714
Equity securities	881		—		—		881		635		—		—		635
Deferred compensation plan	124		—		—		124		116		—		—		116
Foreign currency derivative contracts	—		78		—		78		—		13		—		13
Total	$	10,279	$	20,273	$	—	$	30,552	$	9,526	$	25,539	$	—	$	35,065

Liabilities:
Deferred compensation plan	$	124	$	—	$	—	$	124	$	116	$	—	$	—	$	116
Foreign currency derivative contracts	—		1		—		1		—		93		—		93
Total	$	124	$	1	$	—	$	125	$	116	$	93	$	—	$	209

Summary of the Classification of Marketable Equity Securities

The following table summarizes the classification of our marketable equity securities in our Consolidated Balance Sheets (in millions):



	December 31, 2018		December 31, 2017
Cash and cash equivalents	$	5,305	$	4,714
Prepaid and other current assets	863		637
Other long-term assets	142		114
Total	$	6,310	$	5,465