Significant Customer Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Revenue, Major Customer [Line Items]
Total sales, As Reported	$ 175,127	$ 173,082	$ 450,680	$ 564,731
Product [Member]
Revenue, Major Customer [Line Items]
Total sales, As Reported	$ 148,138	$ 144,843	$ 366,443	$ 485,287
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	22.20%	35.00%	24.20%	35.10%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member] | Product [Member]
Revenue, Major Customer [Line Items]
Total sales, As Reported	$ 38,957	$ 60,546	$ 108,978	$ 198,159
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Lam Research [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Percentage	12.60%	11.50%	13.60%	16.40%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Lam Research [Member] | Product [Member]
Revenue, Major Customer [Line Items]
Total sales, As Reported	$ 21,991	$ 19,878	$ 61,364	$ 92,368
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Applied Materials, Inc. [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Amount	$ 30,669		$ 30,669		$ 34,301
Concentration Risk, Percentage			12.30%		34.20%
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Lam Research [Member]
Revenue, Major Customer [Line Items]
Concentration Risk, Amount					$ 12,181
Concentration Risk, Percentage					12.10%