Other Current and Long-Term Assets (Schedule of Other Current Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets, Noncurrent [Abstract]
Prepaid expenses	$ 30,314	$ 28,967
Taxes receivable	14,098	35,475
Customer acquisition costs	34,515	23,520
Contract assets	9,670	0
Deferred sales commission	4,464	0
Other assets	15,159	13,178
Other current assets	$ 108,220	$ 101,140