Segment Reporting, Geographic Information, and Significant Customers - Summary of Customers Comprising More Than 10% in Net Revenue (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Revenues | Customer Concentration Risk
Concentration Risk [Line Items]
Concentration risk	49.00%	62.00%	64.00%
Net Revenues | Customer Concentration Risk | Samsung Electronics
Concentration Risk [Line Items]
Concentration risk	0.00%	33.00%	32.00%
Net Revenues | Customer Concentration Risk | Customer B
Concentration Risk [Line Items]
Concentration risk	20.00%	13.00%	18.00%
Net Revenues | Customer Concentration Risk | Customer C
Concentration Risk [Line Items]
Concentration risk	18.00%	14.00%	14.00%
Net Revenues | Customer Concentration Risk | Customer D
Concentration Risk [Line Items]
Concentration risk	11.00%	2.00%	0.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer C
Concentration Risk [Line Items]
Concentration risk		18.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer E
Concentration Risk [Line Items]
Concentration risk	55.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer F
Concentration Risk [Line Items]
Concentration risk	26.00%	46.00%	31.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer G
Concentration Risk [Line Items]
Concentration risk		16.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer H
Concentration Risk [Line Items]
Concentration risk			44.00%
Outstanding Accounts and Other Receivable | Credit Concentration Risk | Customer I
Concentration Risk [Line Items]
Concentration risk			11.00%