Long-Term Debt, Debt Facilities (Details) $ in Thousands, ¥ in Billions		12 Months Ended
		Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2018 JPY (¥)	Apr. 18, 2018 USD ($)	Dec. 31, 2017 JPY (¥)	Jun. 16, 2016 USD ($)	Oct. 09, 2014 USD ($)	Oct. 09, 2014 JPY (¥)
Long-term Debt [Abstract]
Balance	[1]	$ 434,455
Current portion of long-term debt		69,455		$ 77,840
Unamortized debt issuance costs		4,000
Interest expense		21,800		22,200	$ 15,600
October 2014 Credit Agreement Term Loan Facility [Member]
Long-term Debt [Abstract]
Original principal amount		127,500								$ 127,500
Balance		$ 0		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 long-term debt		$ 20,000
October 2014 Credit Agreement Japanese Yen Term Loan Facility [Member]
Long-term Debt [Abstract]
Original principal amount | ¥						¥ 6.6					¥ 6.6
Balance		$ 0		43,500		¥ 0.0		¥ 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
October 2014 Credit Agreement Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Balance		$ 0		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 and credit line was closed.
Term of loan		5 years
April 2018 Credit Agreement Term Loan Facility [Member]
Long-term Debt [Abstract]
Original principal amount		$ 400,000					$ 400,000
Balance		$ 385,000	[2],[3]	0
Interest rate		Variable 30 day: 4.77%
Interest rate		4.77%				4.77%
Term of variable rate		30 days
Repayment terms		35% of the principal amount is payable in increasing quarterly installments over a five-year period that began on June 30, 2018, with the remainder payable at the end of the five-year term.
Percentage of principal payable in installments		35.00%
Frequency of payment		Quarterly
Term of loan		5 years
April 2018 Credit Agreement Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Balance		$ 49,500	[2],[3]	0
Interest rate		Variable 30 day: 4.77%
Interest rate		4.77%				4.77%
Term of variable rate		30 days
Repayment terms		Revolving line of credit expires April 18, 2023.
Term of loan		5 years
Japan Subsidiary Loan [Member]
Long-term Debt [Abstract]
Original principal amount | ¥						¥ 2.0
Balance		$ 0		5,900		¥ 0.0		¥ 0.7
Interest rate		0.66%				0.66%
Repayment terms		Principal amount was paid in full during July 2018.
Convertible Note [Member]
Long-term Debt [Abstract]
Original principal amount		$ 210,000							$ 210,000
Balance		$ 0		$ 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.
Interest expense		$ 3,500

[1] The carrying value of the debt reflects the amounts stated in the above table less a debt discount of $4.0 million, which is not reflected in this table.

[2] As of December 31, 2018, the current portion of the Company's debt (i.e. becoming due in the next 12 months) included $20.0 million of the balance of its U.S. dollar denominated debt under the New Credit Agreement facility. The Company has classified the $49.5 million borrowed under the revolving line of credit as short term because it is the Company's intention to use the line of credit to borrow and pay back funds over short periods of time.

[3] The carrying value of the debt reflects the amounts stated in the above table less a debt issuance costs of $4.0 million, which is not reflected in this table.