Nature of Business and Basis of Presentation Revision of Prior Period Amounts (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
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
As previously reported [Member]
Cost of revenues		107,457		210,023
Research and development		17,542		35,022
Sales and marketing		75,882		143,172
General and administrative		57,997		113,703
Amortization of acquired intangible assets		5,463		10,230
Restructuring charge (benefit)		(46)		14
Total costs and operating expenses		264,295		512,164
Adjustment [Member]
Cost of revenues		23,803		46,162
Research and development		0		0
Sales and marketing		(19,402)		(37,697)
General and administrative		(4,401)		(8,465)
Amortization of acquired intangible assets		0		0
Restructuring charge (benefit)		0		0
Total costs and operating expenses		$ 0		$ 0