Other Current and Long-Term Assets (Schedule of Other Current Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Other Assets, Noncurrent [Abstract]
Customer acquisition costs	$ 43,751	$ 39,329
Prepaid expenses	34,556	31,992
Contract assets, net	23,837	17,659
Taxes receivable	19,476	20,516
Deferred sales commissions	5,738	5,202
Other	10,150	10,284
Other current assets	$ 137,508	$ 124,982