CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Revenue	$ 560,155	$ 430,798	$ 422,723
Cost of revenue	242,249	190,856	187,922
Gross profit	317,906	239,942	234,801
Operating expenses:
Sales and marketing (includes stock-based compensation of $3,320, $1,280 and $1,907 for 2011, 2010 and 2009, respectively)	65,996	45,750	53,719
General and administrative (includes stock-based compensation of $7,829, $5,815 and $6,034 for 2011, 2010 and 2009, respectively)	59,906	53,536	60,373
Technology (includes stock-based compensation of $2,873, $849 and $928 for 2011, 2010 and 2009, respectively)	49,276	35,047	25,050
Amortization of intangible assets acquired in business combinations	16,646	13,089	13,128
Total operating expenses	191,824	147,422	152,270
Income from operations	126,082	92,520	82,531
Interest and other income, net	4,666	2,204	302
Income before income taxes	130,748	94,724	82,833
Income tax expense	29,618	14,120	21,264
Income from continuing operations	101,130	80,604	61,569
Discontinued operations (Note 5):
(Loss) income from discontinued operations, net of tax benefit of $88 in 2010 and tax expense of $4,008 in 2009	0	(134)	7,047
Gain on sale, net of tax benefit of $8,944	0	10,040	0
Net income from discontinued operations	0	9,906	7,047
Net income	101,130	90,510	68,616
Other comprehensive income:
Change in market value of marketable securities, net of tax	0	5,524	2,577
Foreign currency translation	(3,749)	(2,056)	5,281
Other comprehensive income, net of tax	(3,749)	3,468	7,858
Total comprehensive income	$ 97,381	$ 93,978	$ 76,474
Basic net income per common share:
Continuing operations	$ 1.26	$ 0.99	$ 0.71
Discontinued operations	$ 0.00	$ 0.12	$ 0.08
Net income	$ 1.26	$ 1.11	$ 0.79
Diluted net income per common share:
Continuing operations	$ 1.24	$ 0.98	$ 0.71
Discontinued operations	$ 0.00	$ 0.12	$ 0.08
Net income	$ 1.24	$ 1.10	$ 0.79
Weighted-average shares used to calculate net income per common share:
Basic	80,323	81,615	86,716
Diluted	81,489	82,334	87,210