Summary of Significant Accounting Policies (Changes in Accumulated Other Comprehensive Loss by Component) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of Significant Accounting Policies
Foreign currency translation, Beginning balance	$ (86,044)	$ (69,417)
Foreign currency translation, Other comprehensive income (loss) before reclassifications	(5,428)	(16,627)
Other comprehensive income (loss), Foreign currency transaction and translation adjustment, net of tax	(5,428)	(16,627)
Foreign currency translation, Ending balance	(91,472)	(86,044)	$ (69,417)
Unrealized gain (loss) on on derivatives, Beginning balance	292	(143)
Unrealized gain (loss) on on derivatives, Other comprehensive income (loss) before reclassifications	355	1,448
Unrealized gain (loss) on on derivatives, Amounts reclassified from accumulated other comprehensive loss	(647)	(1,013)
Unrealized gain (loss) on on derivatives, Net other comprehensive income (loss), net of tax	(292)	435	(125)
Unrealized gain (loss) on on derivatives, Ending balance		292	(143)
Accumulated other comprehensive income (loss), Beginning balance	(85,752)	(69,560)
Total, Other comprehensive loss before reclassifications	(5,073)	(15,179)
Total, Amounts reclassified from accumulated other comprehensive loss	(647)	(1,013)
Total, Net other comprehensive loss, net of tax	(5,720)	(16,192)
Accumulated other comprehensive income (loss), Ending balance	$ (91,472)	$ (85,752)	$ (69,560)