Debt, Debt Facilities (Details) $ in Thousands, ¥ in Billions	3 Months Ended
	Mar. 31, 2018 USD ($)		Mar. 31, 2018 JPY (¥)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 JPY (¥)	Jun. 16, 2016 USD ($)	Oct. 09, 2014 USD ($)	Oct. 09, 2014 JPY (¥)
Debt [Abstract]
Current portion of debt	$ 362,659			$ 77,840
Unamortized debt issuance costs	1,700
Term Loan Facility [Member]
Debt [Abstract]
Original principal amount	127,500						$ 127,500
Balance	$ 90,800	[1],[2]		94,800
Interest rate	Variable 30 day: 4.627%
Interest rate	4.627%		4.627%
Term of variable rate	30 days
Repayment terms	Principal amount was paid in full during April 2018.
Term of loan	5 years
Current portion of debt	$ 17,500
Japanese Yen Term Loan Facility [Member]
Debt [Abstract]
Original principal amount | ¥			¥ 6.6					¥ 6.6
Balance	$ 44,200	[1],[2]	¥ 4.7	43,500	¥ 4.9
Interest rate	Variable 30 day: 2.7595%
Interest rate	2.7595%		2.7595%
Term of variable rate	30 days
Repayment terms	Principal amount was paid in full during April 2018.
Term of loan	5 years
Current portion of debt	$ 8,500
Revolving Credit Facility [Member]
Debt [Abstract]
Balance	$ 122,500	[1],[2]		47,500
Interest rate	Variable 30 day: 4.594%
Interest rate	4.594%		4.594%
Term of variable rate	30 days
Repayment terms	Principal amount was paid in full during April 2018.
Term of loan	5 years
Japan Subsidiary Loan [Member]
Debt [Abstract]
Original principal amount | ¥			¥ 2.1
Balance	$ 4,100	[1],[2]	¥ 0.4	5,900	¥ 0.7
Interest rate	0.66%		0.66%
Repayment terms	Payable in semi-annual installments over three years that began on January 31, 2016.
Frequency of payment	Semi-annual
Term of loan	3 years
Current portion of debt	$ 4,100
Convertible Note [Member]
Debt [Abstract]
Original principal amount	210,000					$ 210,000
Balance	$ 210,000	[1],[2]		$ 210,000
Interest rate	7.10%		7.10%
Interest rate	4.75%		4.75%
Repayment terms	Principal amount was paid in full during April 2018.

[1] As of March 31, 2018, the current portion of the Company's debt (i.e. becoming due in the next 12 months) included $17.5 million of the balance of its U.S. dollar denominated debt under the Credit Agreement facility, $8.5 million of the balance of its Japanese yen-denominated debt under the Credit Agreement facility, $4.1 million of the Japan subsidiary loan and the $210.0 million convertible note. The Company classified the $122.5 million borrowed under the revolving line of credit as short term because it was the Company's intention to use the line of credit to borrow and pay back funds over short periods of time.

[2] The carrying value of the debt reflects the amounts stated in the above table less debt issuance costs of $1.7 million related to the Credit Agreement, which is not reflected in this table.