Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table summarizes, for assets or liabilities measured at fair value, the respective fair value and the classification by level of input within the fair value hierarchy (in millions):

			Fair Value Measurement at Reporting Date Using
Description	December 31, 2015		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents:
Money market funds	$	2,409	$	2,409	$	—	$	—
U.S. government securities	597		597		—		—
U.S. government agency securities	145		145		—		—
Corporate debt securities	53		—		53		—
Marketable securities:
U.S. government securities	5,948		5,948		—		—
U.S. government agency securities	4,475		4,475		—		—
Corporate debt securities	3,104		—		3,104		—
Total cash equivalents and marketable securities	$	16,731	$	13,574	$	3,157	$	—
Other liabilities:
Contingent consideration liability	$	260	$	—	$	—	$	260

			Fair Value Measurement at Reporting Date Using
Description	December 31, 2014		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3
Cash equivalents:
Money market funds	$	2,153	$	2,153	$	—	$	—
Marketable securities:
U.S. government securities	2,830		2,830		—		—
U.S. government agency securities	2,710		2,710		—		—
Corporate debt securities	1,344		—		1,344		—
Total cash equivalents and marketable securities	$	9,037	$	7,693	$	1,344	$	—
Other liabilities:
Contingent consideration liability	$	191	$	—	$	—	$	191