Notes Payable and Long-Term Debt (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2018 TWD ($)	Jun. 30, 2018 USD ($)	Jun. 19, 2018 TWD ($)	Dec. 31, 2017 USD ($)
Notes payable and long-term debt		$ 61,029		$ 49,559
Current portion of notes payable and long-term debt		(3,161)		(559)
Long term portion of notes payable and long-term debt		57,868		49,000
Term loan 1
Notes payable and long-term debt		21,142
Term loan 1 | London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	1.15%
Term loan 2
Notes payable and long-term debt		$ 4,887
Term loan 2 | London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	1.30%
Note payable 1
Notes payable and long-term debt				559
Stated interest rate	4.50%	4.50%
Revolving Line of Credit 7
Notes payable and long-term debt	$ 0
Revolving line of credit maximum borrowing capacity			$ 300,000,000
Minimum | Revolving Line of Credit 7
Stated interest rate			1.95%
Maximum | Revolving Line of Credit 7
Stated interest rate			2.00%
Revolving Line of Credit | Revolving Line of Credit 1
Notes payable and long-term debt		$ 35,000		$ 49,000
Revolving line of credit maximum borrowing capacity		$ 60,000
Debt maturity date	Sep. 28, 2020
Revolving Line of Credit | Revolving Line of Credit 1 | London Interbank Offered Rate (LIBOR)
Basis spread on variable rate	1.40%