Basis of Condensed Consolidated Financial Statements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019	Dec. 31, 2018
Equity in (losses)/earnings of affiliates, net of tax	$ (422)	$ 233
Revenue from related parties		300
Costs and Expenses, Related Party	200	3,300
Possible indemnification exposure, maximum	25,000
Deferred income tax assets and other current assets	700			$ 600
Disposal group, liabilities current	2,100			2,200
Tax escrow deposits	5,700,000			696,000
Reserves incorrect disposition of assets	20,400			21,200
Increase in contingent consideration value	400	$ 400
Operating	64,606		$ 67,700	0
Total	$ 99,560		$ 103,900
Minimum
Escrow deposits, period held by the Company (in business days)	2 days
Maximum
Escrow deposits, period held by the Company (in business days)	5 days
Accounts Payable and Accrued Liabilities
Reserves incorrect disposition of assets	$ 9,200			$ 9,200
Ten Largest Clients | Sales Revenue, Net | Customer Concentration Risk
Concentration risk, percentage	29.00%	34.00%