Customer Financing (Financing Receivable Credit Quality Indicators) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	$ 142
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	82
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	15
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	294
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	177
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	629
Total financing receivables	1,339	$ 1,472
BBB Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	307
Total financing receivables	307
BB Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	135
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	49
Financing Receivable, Year Three, Originated, Two Years before Current Fiscal Year	15
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	143
Total financing receivables	342
B Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	52
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	167
Total financing receivables	219
CCC Credit Rating [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Financing Receivable, Year One, Originated, Current Fiscal Year	7
Financing Receivable, Year Two, Originated, Fiscal Year before Current Fiscal Year	33
Financing Receivable, Year Four, Originated, Three Years before Current Fiscal Year	242
Financing Receivable, Year Five, Originated, Four Years before Current Fiscal Year	177
Financing Receivable, Originated, More than Five Years before Current Fiscal Year	12
Total financing receivables	$ 471