Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands						1 Months Ended	2 Months Ended	12 Months Ended
	Mar. 08, 2018	Dec. 28, 2017	Oct. 02, 2017	Mar. 29, 2017	Mar. 22, 2017	Jan. 31, 2018	Dec. 28, 2017	Dec. 31, 2017	Mar. 01, 2017	Dec. 31, 2016
Subsidiary Sale Of Stock [Line Items]
Redeemable preferred stock carrying value								$ 23,603		$ 23,603
Redeemable preferred stock authorized								20,000,000		20,000,000
Redeemable preferred stock, price per share								$ 0.0001		$ 0.0001
Preferred stock, shares issued								5,000
Exercise price of warrants (dollars per share)					$ 2.00
Warrant expiration period					5 years			5 years
Stockholder approval date								Jun. 15, 2017
Preferred stock, stated value per share								$ 0.0001		$ 0.0001
Value of common stock issued								$ 17,118
Subsequent Event
Subsidiary Sale Of Stock [Line Items]
Aggregate gross proceeds for private placement	$ 39,700
Securities Purchase Agreements | Patrick Miles And Quentin Blackford
Subsidiary Sale Of Stock [Line Items]
Exercise price of warrants (dollars per share)		$ 5					$ 5
Value of common stock issued		$ 4,000
Securities Purchase Agreements | Subsequent Event | Patrick Miles And Quentin Blackford
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of common stock						$ 300,000,000
Wainwright Warrants
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)								471,600
Exercise price of warrants (dollars per share)								$ 2.50	$ 2.50
Aggregate gross proceeds for private placement				$ 18,900
Maximum
Subsidiary Sale Of Stock [Line Items]
Beneficial ownership limitation percentage								4.99%
Beneficial ownership, limitation option, percentage								9.99%
Beneficial ownership limitation notification period								61 days
Maximum | Certificate of Designation
Subsidiary Sale Of Stock [Line Items]
Convertible preferred stock, percentage of shares issuable upon conversion				19.99%
Maximum | Wainwright Warrants
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)									471,600
Minimum
Subsidiary Sale Of Stock [Line Items]
Percentage of outstanding voting stock acquired								50.00%
Common Stock
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock upon securities purchase agreement					1,809,628
Common stock purchase price share					$ 2.00
Number of warrants issued (in shares)								7,763,582
Exercise price of warrants (dollars per share)								$ 2.00
Value of common stock issued								$ 1
Common Stock | Securities Purchase Agreements
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)								1,700,000
Gain recognized in reduction of fair value of warrant							$ 12,000
Proceeds from exercise of warrant								$ 3,300
Common Stock | Securities Purchase Agreements | Patrick Miles And Quentin Blackford
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock upon securities purchase agreement		1,769,912
Common stock purchase price share			$ 2.26
Number of warrants issued (in shares)		1,327,434					1,327,434
Common Stock | Maximum
Subsidiary Sale Of Stock [Line Items]
Number of warrants issued (in shares)					9,432,000
Common Stock | Maximum | Securities Purchase Agreements | Patrick Miles And Quentin Blackford
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock upon securities purchase agreement			1,769,912
Common Stock | Minimum | Securities Purchase Agreements | Patrick Miles And Quentin Blackford
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock upon securities purchase agreement			1,549,116
Redeemable Preferred Stock
Subsidiary Sale Of Stock [Line Items]
Redeemable preferred stock carrying value								$ 23,600		$ 23,600
Redeemable preferred stock authorized								20,000,000		20,000,000
Redeemable preferred stock redemption, price per share								$ 9.00		$ 9.00
Redeemable preferred stock, price per share								$ 7.11		$ 7.11
Series A convertible preferred stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock, shares issued					15,245			15,245,000
Shares issued price per share					$ 1,000
Percentage of outstanding preferred stock shares				75.00%
Series A convertible preferred stock | Certificate of Designation
Subsidiary Sale Of Stock [Line Items]
Preferred stock convertible to common stock				500,000
Preferred stock, stated value per share				$ 1,000
Series A convertible preferred stock | Common Stock
Subsidiary Sale Of Stock [Line Items]
Preferred stock convertible to common stock					7,622,372