Summary of Significant Accounting Policies - Net Income per Common Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Anti-dilutive common stock equivalents related to options and restricted stock awards excluded from fully diluted calculation	228	162	766
Weighted Average Number of Shares Outstanding Reconciliation [Abstract]
Weighted average common shares outstanding—basic	16,419	15,834	15,625
Dilutive common shares issuable in connection with stock plans	0	0	209
Weighted average common shares outstanding—diluted	16,419	15,834	15,834