Net Income (Loss) per Common Share (Basic and Diluted Income (Loss) Per Share) (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Basic and diluted net loss per common share calculation:
Net loss and comprehensive loss	$ 10,769,000	$ 13,873,000	$ (3,724,000)	$ 2,566,000	$ 23,109,000
Accretion of redeemable convertible preferred stock	(1,828,000)	(318,000)	(2,166,000)	(632,000)
Net income (loss) attributable to common stockholders	$ 8,941,000	$ 13,555,000	$ (5,890,000)	$ 1,934,000
Weighted average number of shares of common stock outstanding - basic	5,667,170	3,671,801	4,960,416	3,661,314
Net income (loss) per share of common stock - basic	$ 1.58	$ 3.69	$ (1.19)	$ 0.53
Weighted average number of shares of common stock outstanding - diluted	7,658,556	6,497,619	4,960,416	6,514,181
Net income (loss) per share of common stock - diluted	$ 1.17	$ 2.09	$ (1.19)	$ 0.30