Description of Business and Summary of Significant Accounting Policies - Narrative (Details)	1 Months Ended			12 Months Ended
	Jun. 30, 2015 USD ($) shares	Mar. 31, 2014 USD ($) $ / shares shares	Sep. 30, 2013 USD ($) shares	Dec. 31, 2015 USD ($) reporting_unit shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares	Sep. 30, 2014 $ / shares
Property, Plant and Equipment [Line Items]
Issuance of common stock in connection with public offering, net of offering costs (in shares) | shares		5,582,215
Price per share (usd per share) | $ / shares		$ 82.00
Aggregated proceeds from sale of shares of common stock, net of underwriters' discounts and commissions		$ 446,500,000
Payments for commissions		11,200,000
Offering expenses		$ 2,200,000
Shares sold by certain selling stockholders (in shares) | shares		8,417,785
Shares sold pursuant to the exercise of vested outstanding options by employees (in shares) | shares		796,846		5,856,000	7,642,000	6,222,000
Net proceeds from issuance of convertible senior notes				$ 896,530,000	$ 0	$ 0
Treasury stock ,value, acquired	$ 150,000,000
Treasury stock, shares, acquired | shares	3,300,000
Number of reporting units | reporting_unit				1
Impairment of goodwill				$ 0	0	0
Warranty term on hardware				1 year
Advertising costs				$ 5,100,000	$ 2,300,000	$ 800,000
Capitalized software development costs				4,300,000
Capitalized computer software amortization				$ 800,000
Stock-based compensation, award requisite service period				4 years
Demonstration units
Property, Plant and Equipment [Line Items]
Useful life				12 months
Software Development
Property, Plant and Equipment [Line Items]
Useful life				3 years
Minimum
Property, Plant and Equipment [Line Items]
Useful life				2 years
Maximum
Property, Plant and Equipment [Line Items]
Useful life				5 years
Convertible Notes Payable
Property, Plant and Equipment [Line Items]
Net proceeds from issuance of convertible senior notes	$ 896,500,000
Series A Convertible Senior Notes
Property, Plant and Equipment [Line Items]
Debt instrument, principal amount	$ 460,000,000
Debt instrument, interest rate	1.00%
Series A Convertible Senior Notes | Convertible Notes Payable
Property, Plant and Equipment [Line Items]
Long-term Debt, Gross				$ 460,000,000
Series B Convertible Senior Notes
Property, Plant and Equipment [Line Items]
Debt instrument, principal amount	$ 460,000,000
Debt instrument, interest rate	1.625%
Series B Convertible Senior Notes | Convertible Notes Payable
Property, Plant and Equipment [Line Items]
Long-term Debt, Gross				$ 460,000,000
IPO
Property, Plant and Equipment [Line Items]
Issuance of common stock in connection with public offering, net of offering costs (in shares) | shares			17,450,000
Shares of common stock from full exercise of over-allotment option granted to underwriters (in shares) | shares			2,275,000
Price per share (usd per share) | $ / shares							$ 20
Aggregated proceeds from sale of shares of common stock, net of underwriters' discounts and commissions			$ 324,600,000
Payments for commissions			24,400,000
Offering expenses			$ 3,600,000
Shares issued from conversion of preferred stock and warrants (shares) | shares			74,221,533