Net Income (Loss) Per Share Attributable to Common Stockholders (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 24, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	2,398,000	704,000	10,833,000
Preferred Stock Dividends, Income Statement Impact	$ 0	$ 0	$ 1,116
Chango
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		$ 18,200		$ 18,200
Business Combination, Contingent Consideration, Threshold Trading Days to Determine Number of Shares		10 days
Contingent consideration, shares issued		971,481
Contingent Consideration, Shares Released From Escrow		126,098
Business Combination, Contingent Consideration, Shares Held in Escrow				126,098
Business Combination, Contingent Consideration, Stock Price Trigger				$ 18.77
iSocket
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High		$ 9,600
Business Combination, Contingent Consideration, Threshold Trading Days to Determine Number of Shares		10 days
Contingent consideration, shares issued		585,170
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	951,000	0	8,113,000
Unvested restricted stock awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	414,000	0	1,750,000
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	611,000	0	845,000
Shares held in escrow
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	392,000	0	125,000
Employee Stock Purchase Plan
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	30,000	0	0
Contingent Shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	0	704,000	0
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	0	0	0
Conversion of preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares excluded from net income (loss) per share	0	0	0