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	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Significant non-cash investing and financing activities
Other payable issued for purchased customer accounts	$ 4,350	$ 9,462
Estimated acquisition earn-out payables and related charges	$ 96,845	71,464
Notes received on the sale of fixed assets and customer accounts		$ 9,903