Net Income Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Denominator
Basic net income per share (in dollars per share)	$ 49.59	$ 44.22	$ 18.27
Weighted-average effect of dilutive securities
Diluted net income per share (in dollars per share)	$ 49.16	$ 43.70	$ 18.00
Class A Common Stock
Numerator
Allocation of undistributed earnings	$ 14,846	$ 13,200	$ 5,438
Denominator
Number of shares used in basic computation (in shares)	299,402	298,548	297,604
Basic net income per share (in dollars per share)	$ 49.59	$ 44.22	$ 18.27
Numerator
Allocation of undistributed earnings for basic computation	$ 14,846	$ 13,200	$ 5,438
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	2,307	2,072	862
Reallocation of undistributed earnings	(126)	(146)	(74)
Allocation of undistributed earnings	$ 17,027	$ 15,126	$ 6,226
Denominator
Number of shares used in basic computation (in shares)	299,402	298,548	297,604
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (in shares)	46,527	46,864	47,146
Restricted stock units and other contingently issuable shares (in shares)	413	689	1,192
Number of shares used in per share computation (in shares)	346,342	346,101	345,942
Diluted net income per share (in dollars per share)	$ 49.16	$ 43.70	$ 18.00
Class B Common Stock
Numerator
Allocation of undistributed earnings	$ 2,307	$ 2,072	$ 862
Denominator
Number of shares used in basic computation (in shares)	46,527	46,864	47,146
Basic net income per share (in dollars per share)	$ 49.59	$ 44.22	$ 18.27
Numerator
Allocation of undistributed earnings for basic computation	$ 2,307	$ 2,072	$ 862
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0
Reallocation of undistributed earnings	(20)	(24)	(14)
Allocation of undistributed earnings	$ 2,287	$ 2,048	$ 848
Denominator
Number of shares used in basic computation (in shares)	46,527	46,864	47,146
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (in shares)	0	0	0
Restricted stock units and other contingently issuable shares (in shares)	0	0	0
Number of shares used in per share computation (in shares)	46,527	46,864	47,146
Diluted net income per share (in dollars per share)	$ 49.16	$ 43.70	$ 18.00
Class C Capital Stock
Numerator
Allocation of undistributed earnings	$ 17,190	$ 15,464	$ 6,362
Denominator
Number of shares used in basic computation (in shares)	346,667	349,728	348,151
Basic net income per share (in dollars per share)	$ 49.59	$ 44.22	$ 18.27
Numerator
Allocation of undistributed earnings for basic computation	$ 17,190	$ 15,464	$ 6,362
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0
Reallocation of undistributed earnings	126	146	74
Allocation of undistributed earnings	$ 17,316	$ 15,610	$ 6,436
Denominator
Number of shares used in basic computation (in shares)	346,667	349,728	348,151
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (in shares)	0	0	0
Restricted stock units and other contingently issuable shares (in shares)	5,547	7,456	9,491
Number of shares used in per share computation (in shares)	352,214	357,184	357,642
Diluted net income per share (in dollars per share)	$ 49.16	$ 43.70	$ 18.00