General - Concentration of Business (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Significant customers
Net revenue	$ 1,170,117	$ 1,158,543	$ 3,392,571	$ 3,431,838
Accounts receivable, net	769,159		$ 769,159		$ 680,569
Minimum
Significant customers
Term of contracts with customers			1 year
Term of contract extensions or renewals			1 year
Notice period for termination of contract			30 days
Maximum
Significant customers
Term of contracts with customers			3 years
Term of contract extensions or renewals			2 years
Notice period for termination of contract			180 days
Pennsylvania Counties
Significant customers
Net revenue			$ 428,600	410,200
CMS
Significant customers
Net revenue			178,300	209,500
Accounts receivable, net	$ 126,100		126,100		$ 117,400
United States federal government
Significant customers
Net revenue			$ 200,100	$ 226,800