Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 266
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	131
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	72
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	13
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	286
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	612
Carrying value of financing receivables	1,380	$ 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	28
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	236
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	176
Carrying value of financing receivables	447
B Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	78
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	50
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	159
Carrying value of financing receivables	287
BB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	188
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	124
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	44
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	13
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	130
Carrying value of financing receivables	499
BBB Credit Rating
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	147
Carrying value of financing receivables	$ 147