Restructuring Costs - Schedule of Costs Accrued and Paid Related to Restructuring (Details) - KFAB Wafer Manufacturing Operations $ in Thousands	6 Months Ended
	Jun. 30, 2018 USD ($)
Restructuring Cost And Reserve [Line Items]
Beginning balance, January 1, 2018	$ 1,304
Costs accrued	512
Restructuring costs paid	(1,816)
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
Costs accrued	526
Restructuring costs paid	$ (1,171)