Consolidated Statements of Balance Sheet (Parenthetical) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	Jul. 31, 2012	Jan. 31, 2012		Oct. 31, 2011		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2011		Oct. 31, 2010		Jul. 31, 2010		Apr. 30, 2010		Jan. 31, 2010		Oct. 31, 2009		Jul. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, trade, net of allowance for doubtful accounts	$ 344	$ 353	[1]	$ 332	[1]	$ 473	[1]	$ 777	[1]	$ 1,027	[1]	$ 994	[1]	$ 919	[1]	$ 879	[1]	$ 1,257	[1]	$ 1,154	[1]	$ 3,767
Preferred stock, par value	$ 0.01	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]
Preferred stock, shares authorized	5,000,000	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]	5,000,000	[1]
Preferred stock, shares issued	0	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]
Preferred stock, shares outstanding	0	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]	0	[1]
Common stock, par value	$ 0.01	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]	$ 0.01	[1]
Common stock, shares authorized	1,400,000,000	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]	1,400,000,000	[1]
Common stock, shares issued	43,926,622	44,264,450	[1]	44,076,160	[1]	43,829,097	[1]	43,824,651	[1]	43,814,824	[1]	43,723,322	[1]	44,039,938	[1]	44,056,151	[1]	44,293,804	[1]	44,931,506	[1]
Common stock, shares outstanding	43,926,622	44,264,450	[1]	44,076,160	[1]	43,829,097	[1]	43,824,651	[1]	43,814,824	[1]	43,723,322	[1]	43,729,338	[1]	44,056,151	[1]	44,293,804	[1]	44,931,506	[1]
As Previously Reported [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, trade, net of allowance for doubtful accounts		353		332		473		777		1,027		994		919		879		1,257		1,154
Preferred stock, par value		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01
Preferred stock, shares authorized		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000		5,000,000
Preferred stock, shares issued		0		0		0		0		0		0		0		0		0		0
Preferred stock, shares outstanding		0		0		0		0		0		0		0		0		0		0
Common stock, par value		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01		$ 0.01
Common stock, shares authorized		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000		1,400,000,000
Common stock, shares issued		44,264,450		44,076,160		43,829,097		43,824,651		43,814,824		43,723,322		44,039,938		44,056,151		44,293,804		44,931,506
Common stock, shares outstanding		44,264,450		44,076,160		43,829,097		43,824,651		43,814,824		43,723,322		43,729,338		44,056,151		44,293,804		44,931,506
Restatement Pricing Adjustment [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, trade, net of allowance for doubtful accounts						473								919
Preferred stock, par value						$ 0.01								$ 0.01
Preferred stock, shares authorized						5,000,000								5,000,000
Preferred stock, shares issued						0								0
Preferred stock, shares outstanding						0								0
Common stock, par value						$ 0.01								$ 0.01
Common stock, shares authorized						1,400,000,000								1,400,000,000
Common stock, shares issued						43,829,097								44,039,938
Common stock, shares outstanding						43,829,097								43,729,338
Restatement Other Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, trade, net of allowance for doubtful accounts						$ 473								$ 919
Preferred stock, par value						$ 0.01								$ 0.01
Preferred stock, shares authorized						5,000,000								5,000,000
Preferred stock, shares issued						0								0
Preferred stock, shares outstanding						0								0
Common stock, par value						$ 0.01								$ 0.01
Common stock, shares authorized						1,400,000,000								1,400,000,000
Common stock, shares issued						43,829,097								44,039,938
Common stock, shares outstanding						43,829,097								43,729,338

[1] As Restated