SUPPLEMENTAL BALANCE SHEET AND CASH FLOW INFORMATION (supplemental cash flow information) (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash and cash equivalents		$ 41,231	$ 123,122	$ 73,620
Cash, cash equivalents, restricted cash and restricted cash equivalents		285,491	229,409	174,811	$ 145,259
Income taxes paid		18,761	24,701	60,764
Interest paid		46,621	22,853	33,227
Non-cash consideration for customer list purchases	[1]	15,528	21,439	10,680
Liabilities for holdback payments on asset purchases and acquisitions		4,121	12,949	3,405
Restricted stock units [Member]
Vesting of restricted stock unit awards		16,646	7,839	4,374
Funds held for customers [Member]
Restricted cash and restricted cash equivalents included in funds held for customers		241,488	106,287	101,191
Other non-current assets [Member]
Non-current restricted cash included in other non-current assets		$ 2,772	$ 0	$ 0

[1] Consists of pre-acquisition amounts owed to us by the sellers.Information regarding operating and finance leases executed in each period can be found in Note 15.