Condensed Consolidated Statements Of Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenues:
Revenues	$ 330,984	$ 322,432	$ 663,377	$ 622,325
Cost of Revenue	56,802	60,266	115,933	111,279
Gross profit	274,182	262,166	547,444	511,046
Operating expenses:
Sales and marketing (1)	92,805	88,446	192,243	175,326
Research, development and engineering (1)	13,606	11,938	29,012	24,922
General and administrative (1)	94,731	105,168	197,902	203,322
Total operating expenses	201,142	205,552	419,157	403,570
Income from operations	73,040	56,614	128,287	107,476
Interest expense, net	22,196	17,335	43,167	33,354
Gain (Loss) on Investments	(3)	(24)	(20,835)	(38)
Other (income) expense, net	(9,059)	(401)	(2,183)	1,800
Income before income taxes and net loss (income) in earnings of equity method investment	59,900	39,656	66,468	72,284
Income tax expense	15,978	11,148	24,681	10,853
Loss (income) on equity method investments	5,821	(4,081)	10,090	(3,607)
Net income	$ 38,101	$ 32,589	$ 31,697	$ 65,038
Net income per common share:
Basic	$ 0.81	$ 0.67	$ 0.67	$ 1.35
Diluted	$ 0.80	$ 0.66	$ 0.65	$ 1.32
Weighted average shares outstanding:
Basic	46,850,944	47,727,786	47,235,859	47,644,729
Diluted	47,437,555	49,102,879	48,279,417	48,806,492
Share-based Payment Arrangement, Expense	$ 6,530	$ 6,862	$ 12,843	$ 11,948
Cost of Sales [Member]
Share-based Payment Arrangement, Expense	143	131	277	263
Selling and Marketing Expense [Member]
Share-based Payment Arrangement, Expense	416	389	814	793
Research and Development Expense [Member]
Share-based Payment Arrangement, Expense	484	361	915	719
General and Administrative Expense [Member]
Share-based Payment Arrangement, Expense	$ 5,487	$ 5,981	$ 10,837	$ 10,173