Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Other Current Assets Disclosure [Abstract]
Prepaid Expense, Current	$ 26,074	$ 29,347
Sales taxes receivable from customers	0	2,218
Due from prior owners of acquired businesses re: working capital settlements	280	284
Interest Receivable, Current	315	515
Income Taxes Receivable, Current	2,522	0
Credit and Debit Card Receivables, at Carrying Value	1,076	1,008
Other Receivables	266	160
Other current assets	$ 30,533	$ 33,532