Stockholders' Equity - Additional Information (Detail) $ / shares in Units, $ in Thousands			6 Months Ended
	Dec. 15, 2017 USD ($) TradingDay $ / shares shares	Mar. 12, 2013 USD ($) $ / shares shares	Jan. 31, 2018 USD ($) $ / shares shares	Jan. 31, 2017 USD ($)	Jul. 31, 2017 $ / shares shares
Equity [Line Items]
Preferred stock, shares issued | shares			0		0
Preferred stock, par value			$ 0.01		$ 0.01
Price per share		$ 4.00
Proceeds from issuance of preferred stock | $			$ 35,000
Common stock par value			$ 0.01		$ 0.01
Issuance of common stock | shares		7,500,000
Proceeds from issuance of common stock, gross | $		$ 30,000
Common stock issuance, transaction cost | $		2,300
Net proceeds from issuance of common stock | $		$ 27,700	$ 3	$ 12
Issuance of warrants to acquire additional shares, shares | shares	2,000,000	2,000,000
Issuance of warrants to acquire additional shares, exercise price		$ 5.00
Warrants expiration term		5 years
Series C Convertible Preferred Stock
Equity [Line Items]
Common stock par value	$ 0.01
Convertible preferred stock conversion price per share	$ 1.96
Preferred stock, dividend rate, percentage	6.00%
Percentage threshold closing sale price of common stock higher than conversion price	170.00%
Series C Convertible Preferred Stock | Minimum
Equity [Line Items]
Trading days | TradingDay	5
Liquidation Basis of Accounting [Member] | Series C Convertible Preferred Stock
Equity [Line Items]
Preferred stock liquidation preference percentage per share	The holders of the Preferred Stock are entitled to receive, prior and in preference to any distribution of any of the assets or funds of the company to the holders of other equity or equity equivalent securities of the Company other than the Preferred Stock by reason of their ownership thereof, an amount per share in cash equal to the sum of (i) one hundred percent (100%) of the stated value per share of Preferred Stock (initially $1,000 per share) then held by them (as adjusted for any stock split, stock dividend, stock combination or other similar transactions with respect to the Preferred Stock), plus (ii) 100% of all declared but unpaid dividends, and all accrued but unpaid dividends on each such share of Preferred Stock, in each case as the date of the triggering event.
Repurchase Agreements | Warrant | Steel Holdings
Equity [Line Items]
Repurchase price of warrant	$ 100
Purchase Agreement | SPHG Holdings | Series C Convertible Preferred Stock
Equity [Line Items]
Preferred stock, shares issued | shares	35,000
Preferred stock, par value	$ 0.01
Price per share	$ 1,000
Proceeds from issuance of preferred stock | $	$ 35,000