Long-Term Debt, Debt Facilities (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2019		Dec. 31, 2018	Apr. 18, 2018
Long-term Debt [Abstract]
Balance	[1]	$ 365,000
Current portion of long-term debt		27,500		$ 69,455
Credit Agreement [Member]
Long-term Debt [Abstract]
Unamortized debt issuance costs		3,000		4,000
Credit Agreement Term Loan Facility [Member]
Long-term Debt [Abstract]
Original principal amount		400,000			$ 400,000
Balance	[3]	$ 365,000	[2]	385,000
Interest rate		Variable 30 day: 3.55%
Interest rate		3.55%
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%
Term of loan		5 years
Current portion of long-term debt		$ 27,500
Credit Agreement Revolving Credit Facility [Member]
Long-term Debt [Abstract]
Balance	[3]	$ 0	[2]	$ 49,500
Repayment terms		Revolving line of credit expires April 18, 2023.
Term of loan		5 years

[1] The carrying value of the debt reflects the amounts stated in the above table less a debt discount of $3.0 million, which is not reflected in this table.

[2] As of December 31, 2019, the current portion of the Company’s debt (i.e. becoming due in the next 12 months) included $27.5 million of the balance of its term loan under the Credit Agreement.

[3] The carrying value of the debt reflects the amounts stated in the above table, less debt issuance costs of $3.0 million and $4.0 million as of December 31, 2019 and 2018, respectively, related to the Credit Agreement, which are not reflected in this table.