Subsequent Events - Additional Information (Detail) (Stockholder Rights Plan)	1 Months Ended
	Aug. 31, 2012
Subsequent Event [Line Items]
Stockholder rights plan, rights issued to common stock holders	1
Stockholder rights plan, number of common share each right entitles to buy	0.001
Stockholder rights plan, rights declared date	Aug. 17, 2012
Minimum
Subsequent Event [Line Items]
Stockholder rights plan, rights issued to common stock holders percentage	15.00%