General - Customers Exceeding Ten Percent of Segment Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Significant customers
Revenues	$ 1,100,075	$ 1,154,289	$ 2,222,454	$ 2,273,295
Healthcare
Significant customers
Revenues	481,021	546,113	969,927	1,052,935
Healthcare | Customer A
Significant customers
Revenues			175,107	161,887
Pharmacy Management
Significant customers
Revenues	$ 624,062	$ 612,658	1,262,275	1,229,118
Pharmacy Management | Customer B
Significant customers
Revenues			$ 195,930	$ 174,535