Condensed Consolidated Statements Of Comprehensive Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues	$ 299,288	$ 288,614
Costs and expenses:
Cost of revenues	48,152	50,669
Sales and marketing	17,275	18,322
Research and development	15,375	13,344
General and administrative	33,067	31,008
Total costs and expenses	113,869	113,343
Operating income	185,419	175,271
Interest expense	(40,788)	(29,023)
Non-operating income (loss), net	7,804	1,301
Income before income taxes	152,435	147,549
Income tax expense	(18,172)	(31,137)
Net Income	134,263	116,412
Other comprehensive income (loss)	243	346
Comprehensive Income	$ 134,506	$ 116,758
Basic income (loss) per share
Net Income	$ 1.38	$ 1.14
Diluted income (loss) per share
Net Income	$ 1.09	$ 0.94
Shares used to compute net income per share
Basic	97,250	102,467
Diluted	123,506	124,464