Allowance for Losses on Financial Assets Allowance for Losses on Financial Assets (Allowance Disclosure) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Allowance for Losses on Financial Assets [Line Items]
Allowance for Credit Loss	$ (797)	$ (840)	$ (747)	$ (802)
Credit Loss Expense, Reversal	57	39
Allowance for Credit Loss, Writeoff	6	1
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Accounts Receivable, Allowance for Credit Loss	(390)	(433)	(390)	(444)
Accounts Receivable, Credit Loss Expense (Reversal)	(7)	(10)
Accounts Receivable, Allowance for Credit Loss, Writeoff	6	1
Credit Loss, Recoveries	1
Accounts Receivable, Allowance for Credit Loss, Recovery	1
Contract with Customer, Asset, Allowance for Credit Loss [Roll Forward]
Contract with Customer, Asset, Allowance for Credit Loss	(76)	(130)	(91)	(129)
Contract with Customer, Asset, Credit Loss Expense (Reversal)	15	1
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Financing Receivable, Allowance for Credit Loss	(66)	(17)	(18)	(17)
Financing Receivable, Credit Loss, Expense (Reversal)	(48)
Other Current Assets
Allowance for Losses on Financial Assets [Line Items]
Allowance for Credit Loss	(57)	(78)	(62)	(72)
Credit Loss Expense, Reversal	5	6
Other Noncurrent Assets
Allowance for Losses on Financial Assets [Line Items]
Allowance for Credit Loss	(208)	(182)	$ (186)	$ (140)
Credit Loss Expense, Reversal	$ 22	$ 42