Additional Information (Schedule of Valuation and Qualifying Accounts) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Discounts [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 0	$ 0	$ 0
Charged to costs and expenses	633	604	620
Deductions	(633)	(604)	(620)
Balance at end of year	0	0	0
Returned Goods [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	32	32	40
Charged to costs and expenses	98	127	97
Deductions	(90)	(127)	(105)
Balance at end of year	40	32	32
Allowance for Losses on Finance Assets [Member]
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	19	19	23
Decrease to allowance	0	0	(4)
Balance at end of year	$ 19	$ 19	$ 19