Fair Value Measurements Fair Value, Assets Measured on Nonrecurring Basis Using Unobservable Inputs (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring fair value losses	$ (72)	$ (317)
Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	120
Nonrecurring fair value losses	(72)	(317)
Level 2 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	103
Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	17	431
Customer Financing Assets | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring fair value losses	(12)	(22)
Customer Financing Assets | Valuation, Market Approach | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	17	100
Customer Financing Assets | Valuation, Market Approach | Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	17	100
Investments | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring fair value losses	(8)	(62)
Investments | Valuation, Income Approach | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		51
Investments | Valuation, Income Approach | Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		51
Property, Plant and Equipment | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring fair value losses	(45)	(75)
Property, Plant and Equipment | Valuation, Income Approach | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		81
Property, Plant and Equipment | Valuation, Income Approach | Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		81
Property, Plant and Equipment | Income and Market Approach | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	103
Property, Plant and Equipment | Income and Market Approach | Level 2 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	103
Other asset sand Acquired intangible assets Member | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring fair value losses	$ (7)	(158)
Other asset sand Acquired intangible assets Member | Valuation, Income Approach | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		199
Other asset sand Acquired intangible assets Member | Valuation, Income Approach | Level 3 | Fair Value, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		$ 199