Restructuring Costs - Schedule of Costs Accrued and Paid Related to Restructuring (Details) - KFAB Wafer Manufacturing Operations $ in Thousands	3 Months Ended
	Mar. 31, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Beginning balance, January 1, 2018	$ 1,304
Costs accrued	(14)
Restructuring costs paid	(1,290)
Retention Costs
Restructuring Cost And Reserve [Line Items]
Beginning balance, January 1, 2018	659
Costs accrued	(14)
Restructuring costs paid	(645)
Equipment Relocation
Restructuring Cost And Reserve [Line Items]
Beginning balance, January 1, 2018	645
Restructuring costs paid	$ (645)