Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues	$ 378,106	$ 331,306	$ 746,152	$ 650,754
Costs and operating expenses:
Cost of revenues	124,705	131,260	245,097	256,185
Research and development	20,597	17,542	42,502	35,022
Sales and marketing	67,825	56,480	130,515	105,475
General and administrative	61,351	53,596	116,731	105,238
Amortization of acquired intangible assets	5,734	5,463	11,794	10,230
Restructuring charge (benefit)	391	(46)	822	14
Total costs and operating expenses	280,603	264,295	547,461	512,164
Income from operations	97,503	67,011	198,691	138,590
Interest income	1,446	1,622	3,002	3,255
Other income, net	341	1,131	209	690
Gain on investments, net	31	4	83	17
Income before provision for income taxes	99,321	69,768	201,985	142,552
Provision for income taxes	37,426	25,529	68,603	55,086
Net income	$ 61,895	$ 44,239	$ 133,382	$ 87,466
Net income per share:
Basic (in dollars per share)	$ 0.35	$ 0.25	$ 0.75	$ 0.49
Diluted (in dollars per share)	$ 0.34	$ 0.24	$ 0.73	$ 0.48
Shares used in per share calculations:
Basic (in shares)	177,891	178,547	177,895	178,333
Diluted (in shares)	181,388	181,817	181,475	182,080