Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 133
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	134
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	75
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	14
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	289
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	664
Carrying value of financing receivables	1,309	$ 1,339
CCC Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	7
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	30
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	238
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	176
Carrying value of financing receivables	451
B Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	51
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	157
Carrying value of financing receivables	208
BB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	133
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	127
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	45
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	14
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	135
Carrying value of financing receivables	454
BBB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	196
Carrying value of financing receivables	$ 196