Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 720,940,000	$ 686,257,000
Other comprehensive income (loss)	6,000	(25,000)
Ending Balance	738,695,000	666,466,000
Foreign  Currency Translation Adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	29,000	9,000
Foreign currency translation adjustments, net of tax of $9 & $1 respectively	6,000	(25,000)
Other comprehensive income (loss)	6,000	(25,000)
Ending Balance	35,000	(16,000)
Other comprehensive income (loss), before reclassifications, tax	$ 0	$ 9,000