Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock Issued	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings
Shares issued at beginning of period (in shares) at Dec. 31, 2018		1,405.9
Total equity at beginning of period at Dec. 31, 2018	$ 22,533	$ 14	$ 21,471	$ 1,178	$ (130)
Total equity at beginning of period (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018						$ (5)	$ (5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	230			230
Other comprehensive loss	93				93
Measurement period adjustment	11		11
Shares issued under employee stock-based compensation plans and other		0.8
Dividends declared, $0.15 per share	(211)			(211)
Stock-based compensation and stock options exercised	23		23
Shares issued at end of period (in shares) at Mar. 31, 2019		1,406.7
Total equity at end of period at Mar. 31, 2019	22,674	$ 14	21,505	1,192	(37)
Shares issued at beginning of period (in shares) at Dec. 31, 2018		1,405.9
Total equity at beginning of period at Dec. 31, 2018	22,533	$ 14	21,471	1,178	(130)
Total equity at beginning of period (Accounting Standards Update 2016-02 [Member]) at Dec. 31, 2018						$ (5)	$ (5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	544
Shares issued at end of period (in shares) at Jun. 30, 2019		1,406.7
Total equity at end of period at Jun. 30, 2019	22,883	$ 14	21,524	1,294	51
Shares issued at beginning of period (in shares) at Mar. 31, 2019		1,406.7
Total equity at beginning of period at Mar. 31, 2019	22,674	$ 14	21,505	1,192	(37)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	314			314
Other comprehensive loss	88				88
Dividends declared, $0.15 per share	(212)			(212)
Stock-based compensation and stock options exercised	19		19
Shares issued at end of period (in shares) at Jun. 30, 2019		1,406.7
Total equity at end of period at Jun. 30, 2019	22,883	$ 14	21,524	1,294	51
Shares issued at beginning of period (in shares) at Dec. 31, 2019		1,406.8
Total equity at beginning of period at Dec. 31, 2019	23,257	$ 14	21,557	1,582	104
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	156			156
Other comprehensive loss	(584)				(584)
Shares issued under employee stock-based compensation plans and other		0.3
Dividends declared, $0.15 per share	(211)			(211)
Stock-based compensation and stock options exercised	22		22
Shares issued at end of period (in shares) at Mar. 31, 2020		1,407.1
Total equity at end of period at Mar. 31, 2020	22,640	$ 14	21,579	1,527	(480)
Shares issued at beginning of period (in shares) at Dec. 31, 2019		1,406.8
Total equity at beginning of period at Dec. 31, 2019	23,257	$ 14	21,557	1,582	104
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	454
Shares issued at end of period (in shares) at Jun. 30, 2020		1,407.2
Total equity at end of period at Jun. 30, 2020	22,923	$ 14	21,624	1,613	(328)
Shares issued at beginning of period (in shares) at Mar. 31, 2020		1,407.1
Total equity at beginning of period at Mar. 31, 2020	22,640	$ 14	21,579	1,527	(480)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	298			298
Other comprehensive loss	152				152
Shares issued under employee stock-based compensation plans and other		0.1
Dividends declared, $0.15 per share	(212)			(212)
Proceeds from controlling shareholder stock transactions	22		22
Stock-based compensation and stock options exercised	23		23
Shares issued at end of period (in shares) at Jun. 30, 2020		1,407.2
Total equity at end of period at Jun. 30, 2020	$ 22,923	$ 14	$ 21,624	$ 1,613	$ (328)