Earnings Per Common Share - Summary of Reconciliation of Earnings (Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Basic Earnings (Loss) per Common Share:
Net loss	$ (8,014)	$ (8,342)	$ (8,038)	$ (8,112)	$ (8,370)	$ (4,240)	$ (6,943)	$ (6,218)	$ (32,506)	$ (25,771)
Distributed earnings to common shares									0	0
Distributed earnings to participating securities									0	0
Total distributed earnings									0	0
Undistributed loss allocable to common shares									(32,506)	(25,771)
Undistributed earnings allocable to participating securities									0	0
Total undistributed loss									(32,506)	(25,771)
Loss to common shares — basic									$ (32,506)	$ (25,771)
Weighted average common shares outstanding — basic	11,443	11,394	11,337	11,266	11,046	10,797	10,266	10,161	11,360	10,571
Basic earnings (loss) per common share	$ (0.70)	$ (0.73)	$ (0.71)	$ (0.72)	$ (0.76)	$ (0.39)	$ (0.68)	$ (0.61)	$ (2.86)	$ (2.44)
Diluted Earnings (Loss) per Common Share:
Loss to common shares — basic									$ (32,506)	$ (25,771)
Undistributed earnings allocated to participating securities									0	0
Undistributed earnings reallocated to participating securities									0	0
Loss to common shares — diluted									$ (32,506)	$ (25,771)
Weighted average common shares outstanding — basic	11,443	11,394	11,337	11,266	11,046	10,797	10,266	10,161	11,360	10,571
Dilutive effect of stock options									0	0
Weighted average common shares outstanding — diluted	11,443	11,394	11,337	11,266	11,046	10,797	10,266	10,161	11,360	10,571
Diluted earnings (loss) per common share	$ (0.70)	$ (0.73)	$ (0.71)	$ (0.72)	$ (0.76)	$ (0.39)	$ (0.68)	$ (0.61)	$ (2.86)	$ (2.44)