Basis of Condensed Consolidated Financial Statements (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018
Revenue from related parties	$ 0	$ 300	$ 0	$ 900
Costs and Expenses, Related Party	400	1,000	1,100	6,300
Non-cash impairment charges	1,500	0	1,511	0
Loss accrual	21,700		21,700
Deferred income tax assets and other current assets	6,300		6,300			$ 600
Disposal group, liabilities current	24,100		24,100			2,200
Tax escrow deposits	1,300,000		1,300,000			700,000
Reserves incorrect disposition of assets	21,400		21,400			21,200
Increase/(decrease) in contingent consideration value		100	(200)	(1,000)
Operating	65,302		65,302		$ 67,700	0
Total	102,683		102,683		$ 103,900
Restricted cash included in other assets	11,616	10,355	11,616	10,355		9,967
Restricted cash included in prepaid expenses and other current assets	2,002	$ 1,070	$ 2,002	$ 1,070		3,012
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	$ 9,300		$ 9,300			$ 9,200
Ten Largest Clients | Sales Revenue, Net | Customer Concentration Risk
Concentration risk, percentage	31.00%	32.00%	30.00%	32.00%