Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2018		169,499
Beginning balance at Dec. 31, 2018	$ 12,111	$ 2	$ 9,062	$ (423)	$ 3,470
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(201)				(201)
Cumulative effect of accounting change on convertible senior notes:
Exercise of long-term incentive stock options (in shares)		64
Exercise of long-term incentive plan stock options and employee stock purchases	6		(1)	7
Purchases of treasury stock (in shares)		(4,753)
Purchases of treasury stock	(653)			(653)
Compensation costs:
Vested compensation awards, net or issued awards (in shares)		737
Vested compensation awards, net	0
Compensation costs included in net loss	100		100
Net income (loss)	773				773
Ending balance (in shares) at Dec. 31, 2019		165,547
Ending balance at Dec. 31, 2019	12,136	$ 2	9,161	(1,069)	4,042
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(364)				(364)
Cumulative effect of accounting change on convertible senior notes:
Equity component	230		230
Capped call	(113)		(113)
Deferred tax provision	(25)		(25)
Exercise of long-term incentive stock options (in shares)		98
Exercise of long-term incentive plan stock options and employee stock purchases	9		(2)	11
Purchases of treasury stock (in shares)		(1,634)
Purchases of treasury stock	(176)			(176)
Compensation costs:
Vested compensation awards, net or issued awards (in shares)		466
Vested compensation awards, net	0
Compensation costs included in net loss	72		72
Net income (loss)	(200)				(200)
Ending balance (in shares) at Dec. 31, 2020		164,477
Ending balance at Dec. 31, 2020	11,569	$ 2	9,323	(1,234)	3,478
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared	(1,658)				(1,658)
Cumulative effect of accounting change on convertible senior notes:
Equity component	(202)		(230)		28
Deferred tax provision	44		50		(6)
Exercise of long-term incentive stock options (in shares)		134
Exercise of long-term incentive plan stock options and employee stock purchases	13		(4)	17
Purchases of treasury stock (in shares)		(1,517)
Purchases of treasury stock	(269)			(269)
Shares issued or reissued for acquisition (in shares)		78,842
Shares issued or reissued for acquisitions	11,116		9,878	1,238
Compensation costs:
Vested compensation awards, net or issued awards (in shares)		842
Vested compensation awards, net	0
Compensation costs included in net loss	73		73
Compensation costs included in net income associated with acquisitions	33		33
Net income (loss)	2,118				2,118
Ending balance (in shares) at Dec. 31, 2021		242,778
Ending balance at Dec. 31, 2021	$ 22,837	$ 2	$ 19,123	$ (248)	$ 3,960