Stock-Based Compensation - Summary and Allocation of Stock-Based Compensation Expense (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Mar. 31, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 14,768		$ 17,202	$ 34,178	$ 53,300
Tax benefit	3,016	900	7,960	6,778	24,663
Stock-based compensation expense related to employee equity awards and employee stock purchases, net of tax	11,752		9,242	27,400	28,637
Cost of sales - product
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	668		686	1,828	2,252
Cost of sales - service
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,102		1,479	3,164	4,600
Cost of revenues
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,770		2,165	4,992	6,852
Sales and marketing
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	4,673		5,889	10,397	19,742
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	3,203		3,669	7,304	12,578
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	5,122		5,479	11,485	14,128
Operating Expenses
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 12,998		$ 15,037	$ 29,186	$ 46,448