General - Concentration of Business (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) item	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Significant customers
Net revenue	$ 1,254,118	$ 1,170,117	$ 3,636,535	$ 3,392,571
Accounts receivable, net	827,169		$ 827,169		$ 743,502
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			$ 448,100	428,600
Pennsylvania Counties One
Significant customers
Net revenue			$ 99,200	93,700
Number of contracts | item			1
CMS
Significant customers
Net revenue			$ 2,900	178,300
Accounts receivable, net	$ 40,700		40,700		$ 69,600
United States federal government
Significant customers
Net revenue			$ 215,400	$ 200,100