Stockholders' Equity - Dividends Declared (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Dividends Payable [Line Items]
Annual dividends declared	$ 1,641	$ 1,408	$ 1,120
Common Stock
Dividends Payable [Line Items]
Cash dividends declared on Class A and Class B common stock, per share	$ 1.64	$ 1.39	$ 1.08
Retained Earnings
Dividends Payable [Line Items]
Annual dividends declared	$ 1,641	$ 1,408	$ 1,120

Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=120397183&loc=d3e187085-122770

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