Segment Information (Subscription Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Total Subscription revenue	$ 775,766	$ 860,945
Subscription [Member]
Segment Reporting Information [Line Items]
Total Subscription revenue	342,129	268,236
Subscription, SaaS [Member]
Segment Reporting Information [Line Items]
Total Subscription revenue	171,081	122,570
Subscription, Non-SaaS [Member]
Segment Reporting Information [Line Items]
Total Subscription revenue	$ 171,048	$ 145,666