Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Denominator
Basic net income per share (in dollars per share)	$ 16.55	$ 10.20	$ 36.69	$ 34.12
Weighted-average effect of dilutive securities
Diluted net income per share (in dollars per share)	$ 16.40	$ 10.12	$ 36.38	$ 33.83
Class A Common Stock
Numerator
Allocation of undistributed earnings	$ 4,973	$ 3,059	$ 11,004	$ 10,218
Denominator
Number of shares used in basic computation (shares)	300,411	299,835	299,934	299,493
Basic net income per share (in dollars per share)	$ 16.55	$ 10.20	$ 36.69	$ 34.12
Numerator
Allocation of undistributed earnings for basic computation	$ 4,973	$ 3,059	$ 11,004	$ 10,218
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	763	475	1,697	1,588
Reallocation of undistributed earnings	(53)	(24)	(103)	(83)
Allocation of undistributed earnings	$ 5,683	$ 3,510	$ 12,598	$ 11,723
Denominator
Number of shares used in basic computation (shares)	300,411	299,835	299,934	299,493
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (shares)	46,108	46,515	46,266	46,549
Restricted stock units and other contingently issuable shares (shares)			105	448
Number of shares used in per share computation (shares)	346,566	346,731	346,305	346,490
Diluted net income per share (in dollars per share)	$ 16.40	$ 10.12	$ 36.38	$ 33.83
Class A Common Stock | Restricted stock units and other contingently issuable shares
Weighted-average effect of dilutive securities
Restricted stock units and other contingently issuable shares (shares)	47	381
Class B Common Stock
Numerator
Allocation of undistributed earnings	$ 763	$ 475	$ 1,697	$ 1,588
Denominator
Number of shares used in basic computation (shares)	46,108	46,515	46,266	46,549
Basic net income per share (in dollars per share)	$ 16.55	$ 10.20	$ 36.69	$ 34.12
Numerator
Allocation of undistributed earnings for basic computation	$ 763	$ 475	$ 1,697	$ 1,588
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0	0
Reallocation of undistributed earnings	(7)	(4)	(14)	(13)
Allocation of undistributed earnings	$ 756	$ 471	$ 1,683	$ 1,575
Denominator
Number of shares used in basic computation (shares)	46,108	46,515	46,266	46,549
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (shares)	0	0	0	0
Restricted stock units and other contingently issuable shares (shares)			0	0
Number of shares used in per share computation (shares)	46,108	46,515	46,266	46,549
Diluted net income per share (in dollars per share)	$ 16.40	$ 10.12	$ 36.38	$ 33.83
Class B Common Stock | Restricted stock units and other contingently issuable shares
Weighted-average effect of dilutive securities
Restricted stock units and other contingently issuable shares (shares)	0	0
Class C Capital Stock
Numerator
Allocation of undistributed earnings	$ 5,511	$ 3,534	$ 12,341	$ 11,866
Denominator
Number of shares used in basic computation (shares)	332,930	346,391	336,361	347,818
Basic net income per share (in dollars per share)	$ 16.55	$ 10.20	$ 36.69	$ 34.12
Numerator
Allocation of undistributed earnings for basic computation	$ 5,511	$ 3,534	$ 12,341	$ 11,866
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0	0
Reallocation of undistributed earnings	53	24	103	83
Allocation of undistributed earnings	$ 5,564	$ 3,558	$ 12,444	$ 11,949
Denominator
Number of shares used in basic computation (shares)	332,930	346,391	336,361	347,818
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (shares)	0	0	0	0
Restricted stock units and other contingently issuable shares (shares)			5,715	5,369
Number of shares used in per share computation (shares)	339,285	351,468	342,076	353,187
Diluted net income per share (in dollars per share)	$ 16.40	$ 10.12	$ 36.38	$ 33.83
Class C Capital Stock | Restricted stock units and other contingently issuable shares
Weighted-average effect of dilutive securities
Restricted stock units and other contingently issuable shares (shares)	6,355	5,077