Restructuring Costs - Schedule of Restructuring Costs, Recorded in Restructuring Expense in Condensed Consolidated Statements of Operations, Incurred (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 2,039	$ 206	$ 6,108
KFAB Wafer Manufacturing Operations
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	2,039	206	6,108
KFAB Wafer Manufacturing Operations | Early Supply Contract Termination
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown			1,985
KFAB Wafer Manufacturing Operations | Cost of Equipment Relocation
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	429	220	501
KFAB Wafer Manufacturing Operations | Asset Retirement Obligation
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	701		935
KFAB Wafer Manufacturing Operations | Retention Costs
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 909	$ (14)	$ 2,687