Stockholders' Equity - Changes in Stockholders Equity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 01, 2019	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Apr. 01, 2018	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Stockholders' equity	$ 53,061	$ 34,995	$ 53,061	$ 34,995	$ 53,061	$ 34,995		$ 48,410		$ 43,549		$ 31,463		$ 27,709
Other comprehensive income (loss)	50	(467)	75	(450)
Net Income	2,625	2,534	6,186	4,163	12,096	6,275
Common stock
Stockholders' equity	5	5	5	5	5	5		5		5		5		5
Treasury stock
Stockholders' equity	(1,837)	(1,837)	(1,837)	(1,837)	(1,837)	(1,837)		(1,837)		(1,837)		(1,837)		(1,837)
Additional paid-in capital
Stockholders' equity	30,035	24,028	30,035	24,028	30,035	24,028		28,059		26,791		22,563		21,389
Stock-based compensation and issuance of employee benefit plan stock	1,976	1,465	3,244	2,639
Accumulated other comprehensive income (loss)
Stockholders' equity	(960)	(934)	(960)	(934)	(960)	(934)		(1,010)		(1,035)		(467)		(484)
Other comprehensive income (loss)	50	(467)	75	(450)
Retained earnings
Stockholders' equity	25,818	13,733	25,818	13,733	$ 25,818	$ 13,733		$ 23,193		$ 19,625		$ 11,199		$ 8,636
Cumulative effect of changes in accounting principles							$ 0		$ 7		$ 0		$ 934
Net Income	$ 2,625	$ 2,534	$ 6,186	$ 4,163