Net Income Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Denominator
Basic net income per share (in dollars per share)	$ 10.21	$ 14.33	$ 20.16	$ 23.91
Weighted-average effect of dilutive securities
Diluted net income per share (in dollars per share)	$ 10.13	$ 14.21	$ 20.00	$ 23.71
Class A Common Stock
Numerator
Allocation of undistributed earnings	$ 3,055	$ 4,286	$ 6,042	$ 7,150
Denominator
Number of shares used in basic computation (shares)	299,308	299,035	299,642	299,025
Basic net income per share (in dollars per share)	$ 10.21	$ 14.33	$ 20.16	$ 23.91
Numerator
Allocation of undistributed earnings for basic computation	$ 3,055	$ 4,286	$ 6,042	$ 7,150
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	473	667	935	1,113
Reallocation of undistributed earnings	(26)	(36)	(53)	(59)
Allocation of undistributed earnings	$ 3,502	$ 4,917	$ 6,924	$ 8,204
Denominator
Number of shares used in basic computation (shares)	299,308	299,035	299,642	299,025
Weighted-average effect of dilutive securities
Conversion of Class B to Class A common shares outstanding (shares)	46,355	46,525	46,383	46,562
Restricted stock units and other contingently issuable shares (shares)			135	482
Number of shares used in per share computation (shares)	345,755	346,013	346,160	346,069
Diluted net income per share (in dollars per share)	$ 10.13	$ 14.21	$ 20.00	$ 23.71
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)	92	453
Class B Common Stock
Numerator
Allocation of undistributed earnings	$ 473	$ 667	$ 935	$ 1,113
Denominator
Number of shares used in basic computation (shares)	46,355	46,525	46,383	46,562
Basic net income per share (in dollars per share)	$ 10.21	$ 14.33	$ 20.16	$ 23.91
Numerator
Allocation of undistributed earnings for basic computation	$ 473	$ 667	$ 935	$ 1,113
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0	0
Reallocation of undistributed earnings	(3)	(6)	(7)	(9)
Allocation of undistributed earnings	$ 470	$ 661	$ 928	$ 1,104
Denominator
Number of shares used in basic computation (shares)	46,355	46,525	46,383	46,562
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)	46,355	46,525	46,383	46,562
Diluted net income per share (in dollars per share)	$ 10.13	$ 14.21	$ 20.00	$ 23.71
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	$ 3,431	$ 4,994	$ 6,818	$ 8,341
Denominator
Number of shares used in basic computation (shares)	336,105	348,409	338,092	348,832
Basic net income per share (in dollars per share)	$ 10.21	$ 14.33	$ 20.16	$ 23.91
Numerator
Allocation of undistributed earnings for basic computation	$ 3,431	$ 4,994	$ 6,818	$ 8,341
Reallocation of undistributed earnings as a result of conversion of Class B to Class A shares	0	0	0	0
Reallocation of undistributed earnings	26	36	53	59
Allocation of undistributed earnings	$ 3,457	$ 5,030	$ 6,871	$ 8,400
Denominator
Number of shares used in basic computation (shares)	336,105	348,409	338,092	348,832
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)			5,394	5,516
Number of shares used in per share computation (shares)	341,269	353,941	343,486	354,348
Diluted net income per share (in dollars per share)	$ 10.13	$ 14.21	$ 20.00	$ 23.71
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)	5,164	5,532