Restructuring Costs - Schedule of Restructuring Costs, Recorded in Restructuring Expense in Condensed Consolidated Statements of Operations, Incurred (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 526	$ 1,838	$ 206	$ 4,069
KFAB Wafer Manufacturing Operations
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	526	1,838	206	4,069
KFAB Wafer Manufacturing Operations | Early Supply Contract Termination
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown		(246)		1,985
KFAB Wafer Manufacturing Operations | Cost of Equipment Relocation
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown	$ 526	72	220	72
KFAB Wafer Manufacturing Operations | Asset Retirement Obligation
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown		234		234
KFAB Wafer Manufacturing Operations | Retention Costs
Restructuring Cost And Reserve [Line Items]
Restructuring costs relating to KFAB shutdown		$ 1,778	$ (14)	$ 1,778