Stockholders' Equity - Additional Information (Detail) | Jan. 14, 2021USD ($) | Jan. 01, 2021USD ($) | Dec. 08, 2020USD ($)$ / sharesshares | Nov. 24, 2020USD ($)$ / sharesshares | Apr. 30, 2020USD ($)$ / shares | Mar. 24, 2017$ / sharesshares | Oct. 28, 2016$ / sharesshares | Dec. 31, 2020USD ($)Vote$ / sharesshares | Dec. 31, 2019USD ($)$ / sharesshares | Dec. 31, 2018USD ($)shares | Dec. 31, 2017shares | Jul. 29, 2015$ / sharesshares |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Preferred stock, shares authorized | | | | | | | | | | | | 50,000,000 |
Preferred stock par value | $ / shares | | | | | | | | | | | | $ 0.01 |
Common stock, voting rights | | | | | | | | Holders of Class A Common Stock and Class B Common Stock will be entitled to one vote for each share held on all matters submitted to stockholders for their vote or approval. | | | | |
Net proceeds from issuance of common stock | $ | | | | | | | | $ 14,426,000 | $ 5,443,000 | | | |
Change in fair value of consideration warrants expense | $ | | | | | | | | 300,000 | $ 800,000 | $ (600,000) | | |
Loan and Security Agreement [Member] | Horizon Technology Finance Corporation and Silicon Valley Bank [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Warrants expiration period | | | | | | | 7 years | | | | | |
Loan and Security Agreement [Member] | Horizon Technology Finance Corporation and Silicon Valley Bank [Member] | Tranche One [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Warrants to purchase shares of common stock | | | | | | | 152,580 | | | | | |
Exercise price of warrants | $ / shares | | | | | | | $ 6.39 | | | | | |
Warrant shares percentage issued of loan amount | | | | | | | 6.00% | | | | | |
Loan and Security Agreement [Member] | Horizon Technology Finance Corporation and Silicon Valley Bank [Member] | Tranche Two [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Warrants to purchase shares of common stock | | | | | | 38,006 | | | | | | |
Exercise price of warrants | $ / shares | | | | | | $ 5.92 | | | | | | |
Warrant shares percentage issued of loan amount | | | | | | 3.00% | 3.00% | | | | | |
Cantor Fitzgerald [Member] | ATM Offering [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Gross proceeds from issuance of common stock | $ | | | | | | | | 13,000,000 | | | | |
Net proceeds from issuance of common stock | $ | | | | | | | | $ 12,500,000 | | | | |
Cantor Fitzgerald [Member] | ATM Offering [Member] | Subsequent Event [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Aggregate offering price | $ | $ 5,500,000 | | | | | | | | | | | |
LPC Purchase Agreement [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Agreement term | | | | 36 months | | | | | | | | |
Class A Common Stock [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Common stock, shares authorized | | | | | | | | 100,000,000 | 100,000,000 | | | 100,000,000 |
Common stock par value | $ / shares | | | | | | | | $ 0.01 | $ 0.01 | | | $ 0.01 |
Common stock, vote per share | Vote | | | | | | | | 1 | | | | |
Common stock, shares outstanding | | | | | | | | 54,050,710 | 40,918,522 | 20,347,065 | 9,693,254 | |
Class A Common Stock [Member] | Cantor Fitzgerald [Member] | ATM Offering [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Common stock par value | $ / shares | | | | | $ 0.01 | | | | | | | |
Shares sold | | | | | | | | 5,480,941 | | | | |
Class A Common Stock [Member] | Cantor Fitzgerald [Member] | ATM Offering [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Aggregate offering price | $ | | | | | $ 13,000,000 | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Shares sold | | | 963,855 | 425,725 | | | | | | | | |
Shares registered under the LPC agreement | | | 5,331,306 | | | | | | | | | |
Percentage of aggregate offering price | | | | 1.50% | | | | | | | | |
Share price | $ / shares | | | $ 2.08 | | | | | | | | | |
Aggregate gross purchase price | $ | | | $ 2,000,000 | | | | | | | | | |
Maximum obligation for number of shares issued per day | | | | 2,000,000 | | | | | | | | |
Purchase price for shares | | | | The purchase price for shares of Class A common stock to be purchased by Lincoln Park under a Regular Purchase will be equal to the lower of (in each case, subject to the adjustments described in the LPC Purchase Agreement): (i) the lowest sale price for the Class A common stock on the applicable purchase date and (ii) the arithmetic average of the three lowest closing sales prices for the Class A common stock during the 10 consecutive trading days prior to the purchase date | | | | | | | | |
Common stock, shares outstanding | | | | 73,880,351 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Subsequent Event [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Gross proceeds from issuance of common stock | $ | | $ 8,000,000 | | | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Aggregate offering price | $ | | | | $ 47,000,000 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Regular Purchase Share Limit [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Number of shares issued per day | | | | 250,000 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Regular Purchase Share Limit Two [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Increase in number of shares issued per day | | | | 275,000 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Regular Purchase Share Limit Two [Member] | Minimum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Share price | $ / shares | | | | $ 4 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Regular Purchase Share Limit Three [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Increase in number of shares issued per day | | | | 300,000 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Regular Purchase Share Limit Three [Member] | Minimum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Share price | $ / shares | | | | $ 5 | | | | | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Additional Accelerated [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Percentage of number of shares issued during period | | | | | | | | 300.00% | | | | |
Percentage of number of common stock shares traded during period | | | | | | | | 30.00% | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Additional Accelerated [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Share price as a percentage of the volume weighted average price | | | | | | | | 97.00% | | | | |
Class A Common Stock [Member] | LPC Purchase Agreement [Member] | Exchange Cap [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Maximum number of shares to be issued as percentage of outstanding | | | | 19.99% | | | | | | | | |
Maximum number of shares to be issued | | | | 14,768,682 | | | | | | | | |
Class A Common Stock [Member] | Lincoln Park Capital Fund, LLC and Affiliates [Member] | Maximum [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Ownership percentage by noncontrolling owners | | | | 9.99% | | | | | | | | |
Class B Common Stock [Member] | | | | | | | | | | | | |
Class Of Stock [Line Items] | | | | | | | | | | | | |
Common stock, shares authorized | | | | | | | | 100,000,000 | 100,000,000 | | | 100,000,000 |
Common stock par value | $ / shares | | | | | | | | $ 0.01 | $ 0.01 | | | $ 0.01 |
Common stock, vote per share | Vote | | | | | | | | 1 | | | | |
Common stock, shares outstanding | | | | | | | | 23,094,221 | 23,094,221 | 23,094,221 | 23,119,246 | |