Financial Instruments (Schedule of Long-Term Debt) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt	$ 491,022	$ 424,029
Less: current portion	(20)	(20)
Long-term debt, net of current portion	491,002	424,009
Credit Agreement [Member]
Debt Instrument [Line Items]
Long-term debt	$ 491,000	$ 424,000
Interest rate	3.15%	3.43%
Maturity date range, end	Dec. 31, 2022
Other Debt [Member]
Debt Instrument [Line Items]
Long-term debt	$ 22	$ 29
Interest rate	5.50%	5.50%
Maturity date range, end	Dec. 31, 2021