Description of Business and Accounting Policies - Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Contract with Customer, Refund Liability	$ 712	$ 623	$ 468
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Contract with Customer, Right to Recover Product	629	519	406
Sales Returns and Allowances
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]
Additions to allowance for returns	2,500	2,300	1,800
Deductions to allowance for returns	$ 2,500	$ 2,300	$ 1,900