Segment Information and Revenue - Schedule of Net Sales by Direct Sales or Distributor and Location (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended		12 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 320,946	$ 285,247	$ 899,543	$ 785,774	$ 1,100,000
Percentage of net sales		100.00%	100.00%	100.00%	100.00%
Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 93,951	$ 85,404	$ 254,630	$ 251,437
Percentage of net sales		100.00%	100.00%	100.00%	100.00%
Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 226,995	$ 199,843	$ 644,913	$ 534,337
Percentage of net sales		100.00%	100.00%	100.00%	100.00%
China
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 173,228	$ 157,235	$ 487,984	$ 433,145
Percentage of net sales		54.00%	55.00%	54.00%	55.00%
China | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 60,037	$ 54,052	$ 164,109	$ 162,241
Percentage of net sales		64.00%	63.00%	64.00%	65.00%
China | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 113,191	$ 103,183	$ 323,875	$ 270,904
Percentage of net sales		50.00%	52.00%	50.00%	51.00%
United States
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 34,959	$ 25,386	$ 90,947	$ 70,361
Percentage of net sales		11.00%	9.00%	10.00%	9.00%
United States | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 4,409	$ 4,688	$ 12,866	$ 13,149
Percentage of net sales		5.00%	5.00%	5.00%	5.00%
United States | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 30,550	$ 20,698	$ 78,081	$ 57,212
Percentage of net sales		13.00%	10.00%	12.00%	11.00%
Korea
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 17,847	$ 17,421	$ 44,311	$ 50,785
Percentage of net sales		6.00%	6.00%	5.00%	6.00%
Korea | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 4,597	$ 5,134	$ 12,148	$ 14,092
Percentage of net sales		5.00%	6.00%	5.00%	6.00%
Korea | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 13,250	$ 12,287	$ 32,163	$ 36,693
Percentage of net sales		6.00%	6.00%	5.00%	7.00%
Germany
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 23,988	$ 21,756	$ 72,344	$ 58,210
Percentage of net sales		7.00%	8.00%	8.00%	7.00%
Germany | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 3,076	$ 3,078	$ 9,001	$ 8,248
Percentage of net sales		3.00%	4.00%	4.00%	3.00%
Germany | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 20,912	$ 18,678	$ 63,343	$ 49,962
Percentage of net sales		9.00%	9.00%	10.00%	9.00%
Singapore
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 17,616	$ 17,901	$ 53,929	$ 43,840
Percentage of net sales		5.00%	6.00%	6.00%	6.00%
Singapore | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 637	$ 461	$ 1,549	$ 635
Percentage of net sales		1.00%	1.00%	1.00%
Singapore | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 16,979	$ 17,440	$ 52,380	$ 43,205
Percentage of net sales		7.00%	9.00%	8.00%	8.00%
Taiwan
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 18,296	$ 15,327	$ 55,095	$ 49,585
Percentage of net sales		6.00%	5.00%	6.00%	6.00%
Taiwan | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 621	$ 578	$ 2,399	$ 5,132
Percentage of net sales		1.00%	1.00%	1.00%	2.00%
Taiwan | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales		$ 17,675	$ 14,749	$ 52,696	$ 44,453
Percentage of net sales		8.00%	7.00%	8.00%	8.00%
All Others
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales	[1]	$ 35,012	$ 30,221	$ 94,933	$ 79,848
Percentage of net sales	[1]	11.00%	11.00%	11.00%	11.00%
All Others | Direct Sales
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales	[1]	$ 20,574	$ 17,413	$ 52,558	$ 47,940
Percentage of net sales	[1]	21.00%	20.00%	20.00%	19.00%
All Others | Distributor
Segment Reporting Revenue Reconciling Item [Line Items]
Net sales	[1]	$ 14,438	$ 12,808	$ 42,375	$ 31,908
Percentage of net sales	[1]	7.00%	7.00%	7.00%	6.00%

[1] Represents countries with less than 3% of the total net sales each.