Financial Instruments (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Long Term Debt Percentage Bearing Fixed Interest Percentage	72.00%
Gain/Loss on FX Effectiveness		$ 0
Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months	$ 1,800
Designated as Hedging Instrument [Member] | Cross Currency Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Amount of Hedged Item	$ 100,000
Derivative, Fixed Interest Rate	0.01%
Gain/Loss on FX Effectiveness	$ 0
Designated as Hedging Instrument [Member] | 2.52% $50 Million Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 50,000
Derivative, Fixed Interest Rate	2.52%
Gain/Loss on IR Effectiveness	$ 0	0
Designated as Hedging Instrument [Member] | 2.25% $100 Million Interest Rate Swap [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Line Of Credit Facility Forecasted Borrowing Amount	$ 100,000
Derivative, Fixed Interest Rate	2.25%
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative, Notional Amount	$ 436,700	394,800
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 1,200	$ 9,400