Equity (Tables)

12 Months Ended

Dec. 31, 2017

Equity [Abstract]

Schedule of common stock outstanding

Shares of Common Stock Outstanding
(in millions)	A		A Special		B
Balance, December 31, 2014	4,272		801		9
Stock compensation plans	25		—		—
Repurchases and retirements of common stock	(125	)	(107	)	—
Employee stock purchase plans	5		—		—
Reclassification of Class A Special common stock	694		(694	)	—
Other	4		—		—
Balance, December 31, 2015	4,875		—		9
Stock compensation plans	23		—		—
Repurchases and retirements of common stock	(161	)	—		—
Employee stock purchase plans	5		—		—
Balance, December 31, 2016	4,742		—		9
Stock compensation plans	19		—		—
Repurchases and retirements of common stock	(131	)	—		—
Employee stock purchase plans	5		—		—
Balance, December 31, 2017	4,635		—		9

Schedule of shares repurchased

Share Repurchases Under Share Repurchase Program Authorization
Year ended December 31 (in millions)	2017		2016		2015
Cash consideration	$	5,000	$	5,000	$	6,750
Shares repurchased	131		161		232

Schedule of accumulated other comprehensive income (loss)

Accumulated Other Comprehensive Income (Loss)
December 31 (in millions)	2017			2016
Unrealized gains (losses) on marketable securities	$	(43	)	$	—
Deferred gains (losses) on cash flow hedges	9			(14		)
Unrecognized gains (losses) on employee benefit obligations	260			219
Cumulative translation adjustments	153			(107		)
Accumulated other comprehensive income (loss), net of deferred taxes	$	379		$	98