Stockholders' Equity (Details Textual) $ / shares in Units, $ in Thousands			12 Months Ended			51 Months Ended
	Jun. 30, 2015 shares	Nov. 14, 2013 shares	Dec. 31, 2019 USD ($) vote $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Mar. 31, 2018 shares	Dec. 31, 2013 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares authorized (in shares)			200,000,000	200,000,000
Common stock, par value (in usd per share) | $ / shares			$ 0.001	$ 0.001
Common stock, number of voting rights | vote			1
Granted (in shares)			0	0	0
Exercises in period, intrinsic value | $			$ 12,453	$ 40,610	$ 22,382
Compensation cost not yet recognized | $			$ 9	$ 142
Compensation cost not yet recognized, period for recognition			1 month 18 days	8 months 17 days
The 2005 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)							4,713,319
Vesting period (in years)			4 years
Granted (in shares)						0
Available for grant (in shares)			0
The 2013 Omnibus Equity Award Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, capital shares reserved for future issuance (in shares)		1,904,633
Vesting period (in years)			4 years
Percentage of outstanding stock reserved for grant		4.00%
Percentage of outstanding stock maximum		5.00%
Capital shares reserved for future issuance, annual increase, maximum			5,530,555
2015 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum employee subscription rate	15.00%
Purchase price of common stock, percent	85.00%
Number of shares authorized (in shares)	500,000
Percent of shares increase, employee stock purchase plan	1.00%
Common stock availability threshold, employee stock purchase plan	2.00%
Shares increase threshold, employee stock purchase plan (in shares)	400,000
Number of additional shares authorized (in shares)			702,163