Stockholders' Equity - Additional information (Detail) - USD ($)			1 Months Ended				12 Months Ended
	Nov. 09, 2018	Aug. 23, 2017	Dec. 31, 2018	May 31, 2018	Mar. 31, 2018	Jul. 11, 2011	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2012	Aug. 02, 2018	Aug. 01, 2018	Feb. 28, 2017	Dec. 03, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, authorized			125,000,000				125,000,000	75,000,000				125,000,000	75,000,000
Preferred Stock, par value			$ 0.001				$ 0.001
Authorized shares of preferred stock			5,000,000				5,000,000
Adjustments to additional paid in capital dividends in excess of retained earnings							$ 12,500,000
Number of RSUs vested							209,500
Company employees, directors and affiliates stock option exercised							350,441	202,519	147,425
Proceeds from common stock							$ 670,000	$ 439,000	$ 297,000
Weighted average grant date fair value of options granted							$ 1.57	$ 1.46	$ 1.75
Number of options granted in period with exercise price below market price							0	0	0
Unrecognized compensation cost related to non-vested share-based compensation awards granted			$ 6,900,000				$ 6,900,000
Unrecognized compensation cost related to non-vested share-based compensation awards granted year							4 years
Options outstanding			4,406,004				4,406,004	2,712,954	3,468,991	3,397,529
Fair value of warrants								$ 6,000,000
2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares of common stock authorized			7,100,000				7,100,000
2011 Equity Incentive Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, authorized			11,050,000				11,050,000
2011 Equity Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares, authorized			18,150,000				18,150,000
Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock options outstanding and exercisable						523,854
Term that options may be awarded						10 years
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity instruments awarded in period							2,034,261
Fair market value of RSUs granted							$ 4,700,000
Vesting period of options							3 years
Restricted Stock Units (RSUs) [Member] | LTIP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity instruments awarded in period							0	0		35,000
Restricted stock units ("RSUs") issued to directors and key employees							1,078,000				978,000
Restricted stock units reserved for future officers										100,000
RSU's Vested per performance criteria during period							8 years
Number of RSUs vested							31,036	9,958	13,347
Series B Non-Voting Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, par value			$ 0.001	$ 0.001			$ 0.001	$ 0.001
Authorized shares of preferred stock			5,000,000				5,000,000	5,000,000
Series B preferred shares outstanding			3,100				3,100	0
Sale and issue of preferred stock				5,000
Purchase price of preferred stock				$ 10,000
Adjustments to additional paid in capital dividends in excess of retained earnings							$ 12,500,000
Series B Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Series B preferred shares outstanding			3,100				3,100
Conversion price				$ 1.80
Series B conversion to Common Stock				27,777,778			(1,900)
Series A Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized shares of preferred stock			2,285,700				2,285,700
Liquidation, dissolution or winding up, holders of the Series A Preferred per share payment															$ 0.001
Series B preferred shares outstanding			2,093,155				2,093,155
Series A Preferred stock converted							0	0	0
Employees and Directors Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company employees, directors and affiliates stock option exercised							400,000	200,000	100,000
Proceeds from common stock							$ 700,000	$ 400,000	$ 300,000
Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding			84,986				84,986
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's securities for shelf registration	$ 150,000,000
Series B conversion to Common Stock							10,555,556
Company employees, directors and affiliates stock option exercised							350,441	202,519	147,426
MidCap Financial Trust [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock									84,986
Exercise price of warrants									$ 3.53
Fair value of warrants									$ 50,000
CRG [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock								349,451						1,701,583
Exercise price of warrants								$ 3.42						$ 2.38
Fair value of warrants								$ 1,500,000						$ 4,500,000
CRG [Member] | Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding			2,051,034				2,051,034
Dr.Mark Sirgo
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period shares upon employee retirement		795,730
Issuance of common stock upon employee retirement			285,305				285,305
Dr. Niraj Vasisht
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock issued during period shares upon employee retirement			65,000		309,162
Issuance of common stock upon employee retirement			198,129				198,129
Directors and Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of equity instruments awarded in period							2,549,177
Fair market value of shares granted							$ 3,900,000
Term of options granted period							10 years
Directors and Employees [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU's Vested per performance criteria during period							1 year
Directors and Employees [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
RSU's Vested per performance criteria during period							3 years