Condensed Consolidated Statements of Stockholders' Equity Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning Balance at Dec. 31, 2018		$ 16	$ (1,717)	$ 17,346	$ (6,953)	$ 33
Beginning Balance (Shares) at Dec. 31, 2018		1,632,148,030
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 424				424
Total other comprehensive income (loss)	$ 54					54
Impact of stock-based compensation plans, net of tax (Shares)		6,001,343
Impact of stock-based compensation plans, net of tax				28
Ending Balance at Mar. 31, 2019		$ 16	(1,717)	17,374	(6,528)	87
Ending Balance (Shares) at Mar. 31, 2019		1,638,149,373
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)					154
Total other comprehensive income (loss)						(9)
Impact of stock-based compensation plans, net of tax (Shares)		949,557
Impact of stock-based compensation plans, net of tax				48
Ending Balance at Jun. 30, 2019		$ 16	(1,717)	17,422	(6,375)	78
Ending Balance (Shares) at Jun. 30, 2019		1,639,098,930
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)					126
Total other comprehensive income (loss)						60
Impact of stock-based compensation plans, net of tax (Shares)		2,243,579
Impact of stock-based compensation plans, net of tax				89
Ending Balance at Sep. 30, 2019		$ 16	(1,717)	17,510	(6,249)	138
Ending Balance (Shares) at Sep. 30, 2019	1,641,342,509
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)					3,996
Total other comprehensive income (loss)						132
Impact of stock-based compensation plans, net of tax (Shares)		1,146,402
Impact of stock-based compensation plans, net of tax				50
Ending Balance at Dec. 31, 2019	$ 13,877	$ 16	(1,717)	17,561	(2,253)	270
Ending Balance (Shares) at Dec. 31, 2019	1,642,488,911
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative Effect of New Accounting Principle in Period of Adoption | Adjustments for New Accounting Pronouncement [Member]					(10)
Net income (loss)	$ 11				11
Total other comprehensive income (loss)	(101)					(101)
Impact of stock-based compensation plans, net of tax (Shares)		4,388,331
Impact of stock-based compensation plans, net of tax				28
Ending Balance at Mar. 31, 2020	$ 13,804	$ 16	$ (1,717)	$ 17,589	$ (2,252)	$ 168
Ending Balance (Shares) at Mar. 31, 2020	1,646,877,242