Supplemental balance sheet and cash flow information (supplemental cash flow information) (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017
Cash and cash equivalents	$ 66,732	$ 59,740	$ 68,594
Total cash, cash equivalents, restricted cash and restricted cash equivalents	144,058	$ 145,259	145,303	$ 128,819
Funds held for customers [Member]
Restricted cash and restricted cash equivalents included in funds held for customers	$ 77,326		$ 76,709