Net Income (Loss) Per Common Share (Anti-Dilutive Common Share Equivalents) (Details) - shares	3 Months Ended		6 Months Ended	12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	1,498,780	60,013,498	12,983,776	60,013,498
Restricted stock units and restricted stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	351,737	0	555,666	0
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	1,125,043	8,179,788	9,911,822	8,179,788
Series A [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	4,438,662	0	4,438,662
Series B [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	10,755,262	0	10,755,262
Series C [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	9,735,538	0	9,735,538
Series C-1 [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	1,701,112	0	1,701,112
Series D [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	14,467,756	0	14,467,756
Series E [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	5,234,546	0	5,234,546
Redeemable Convertible Preferred Stock [Member] | Warrants to purchase [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	0	1,423,768	0	1,423,768
Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	2,206,496
Common Stock [Member] | Warrants to purchase [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive common share equivalents	22,000	4,077,066	2,516,288	4,077,066