Income Taxes - Components of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Capitalized research expenditures	$ 28	$ 32
Deferred revenue	21	21
Tax credits	28	31
Net operating loss carryforwards	394	338
Other accruals	20	20
Inventory items	20	20
Capitalized software costs	8	14
Sales return/rebate reserve	41	33
Share-based compensation expense	15	12
Accrued bonus	3	1
Unrealized gain and losses on securities and investments	0	8
Valuation allowance	(56)	(134)
Total deferred tax assets	522	396
Deferred tax liabilities:
Depreciation and amortization	411	275
Unrealized gains and losses on securities and investments	2	0
Undistributed earnings	3	2
Total deferred tax liabilities	416	277
Net deferred tax assets	$ 106	$ 119