Segment Information - Foreign and U.S. Revenues from External Customers (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues from external customers	$ 172,529	$ 159,157	$ 152,176
United States
Disaggregation of Revenue [Line Items]
Revenues from external customers	166,626	154,042	147,332
Foreign countries
Disaggregation of Revenue [Line Items]
Revenues from external customers	5,903	5,115	4,844
Revenues, disposal group	$ 3,200	$ 3,100	$ 2,900