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Consolidated Statement of Stockholder's Equity - USD ($) $ in Millions	Total	Common Stock	Capital in excess of par value	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock	Scenario, Previously Reported	Scenario, Previously Reported Common Stock	Scenario, Previously Reported Capital in excess of par value	Scenario, Previously Reported Retained earnings	Scenario, Previously Reported Accumulated other comprehensive income (loss)	Scenario, Previously Reported Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting standards	$ (596)	$ 0	$ 0	$ (596)	$ 0	$ 0
Balance at beginning of period at Dec. 31, 2015	6,762	808	1,374	8,813	(1,051)	(3,182)	$ 7,358	$ 808	$ 1,374	$ 9,409	$ (1,051)	$ (3,182)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	(1,750)	0	0	0	0	(1,750)
Issuance of common and treasury stock pursuant to Employee stock plans	20	0	8	0	0	12
Issuance of stock for conversion of debt	43		(5)
Conversion of 5.25% senior notes to common stock		0		0	0	48
Share-based compensation	33	0	33	0	0	0
Cash dividends	(235)	0	0	(235)	0	0
Comprehensive income	2,911	0	0	2,183	728	0
Balance at end of period at Dec. 31, 2016	7,784	808	1,410	10,761	(323)	(4,872)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	(1,600)	0	0	0	0	(1,600)
Issuance of common and treasury stock pursuant to Employee stock plans	14	0	4	0	0	10
Share-based compensation	37	0	37	0	0	0
Cash dividends	(286)	0	0	(286)	0	0
Comprehensive income	3,692	0	0	3,357	335	0
Balance at end of period at Dec. 31, 2017	9,641	808	1,451	13,832	12	(6,462)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock	(2,000)	0	0	0	0	(2,000)
Issuance of common and treasury stock pursuant to Employee stock plans	23	0	13	0	0	10
Share-based compensation	46	0	46	0	0	0
Cash dividends	(348)	0	0	(348)	0	0
Comprehensive income	2,491	0	0	2,465	26	0
Balance at end of period at Dec. 31, 2018	9,853	808	1,510	15,967	20	(8,452)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of new accounting standards	$ 0	$ 0	$ 0	$ 18	$ (18)	$ 0