Net Loss Per Share (Anti-Dilutive Common Share Equivalents) (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti–dilutive common share equivalents (in shares)	1,597,387	1,599,196	1,292,328
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti–dilutive common share equivalents (in shares)	549,907	759,719	778,385
Restricted stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti–dilutive common share equivalents (in shares)	1,047,480	839,477	513,943