Supplemental Disclosures of Cash Flow Information and Non-Cash Financing and Investing Activities - Summary of Significant Non-Cash Investing and Financing Activities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Significant non-cash investing and financing activities
Other payable issued for purchased customer accounts	$ 2,165	$ 2,159
Estimated acquisition earn-out payables and related charges	$ 74,754	23,966
Notes received on the sale of fixed assets and customer accounts		$ 2,045