Reconciliation of Basic and Diluted Earnings Per Share (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jan. 26, 2013	Jan. 28, 2012	Jan. 26, 2013	Jan. 28, 2012
Numerator for basic income (loss) per share:
Net income (loss)	$ (6,058)	$ 52,031	$ (47,613)	$ (11,138)
Preferred stock dividends	(3,942)	(3,963)	(11,825)	(7,081)
Accretion of dividends on preferred stock	(739)	(316)	(1,508)	(578)
Less allocation of earnings and dividends to participating securities		(2,735)
Net income (loss) available to common shareholders	(10,739)	45,017	(60,946)	(18,797)
Numerator for diluted income (loss) per share:
Net income (loss) available to common shareholders	(10,739)	45,017	(60,946)	(18,797)
Preferred stock dividends	3,942	3,963	11,825	7,081
Accretion of dividends on preferred stock	739	316	1,508	578
Effect of dilutive options		3
Net income (loss) available to common shareholders	(10,739)	49,299	(60,946)	(18,797)
Denominator for basic income (loss) per share:
Basic weighted average common shares	58,316	57,371	58,168	57,261
Denominator for diluted income (loss) per share:
Basic weighted average common shares	58,316	57,371	58,168	57,261
Preferred shares		$ 12,000
Average dilutive options		76
Diluted weighted average common shares	58,316	69,447	58,168	57,261
Income (loss) per common share:
Basic	$ (0.18)	$ 0.78	$ (1.05)	$ (0.33)
Diluted	$ (0.18)	$ 0.71	$ (1.05)	$ (0.33)