Shareholders' Equity - Stock Plan Terms and Stock Options Activity (Details) (USD $)	12 Months Ended
Apr. 27, 2013	Apr. 28, 2012	Apr. 30, 2011	May 01, 2010
2010 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grant	2,000,000
Number of shares available for grant	596,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Awarded (in shares)	120,000	128,000	128,000
2010 Stock Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term	10 years	10 years	10 years
Annual vesting percentage	33.30%	33.30%	33.30%
Award vesting period	3 years	3 years	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - beginning balance (in shares)	240,000	128,000
Awarded (in shares)	120,000	128,000
Exercised (in shares)	0	0
Cancelled (in shares)	0	(16,000)
Outstanding - ending balance (in shares)	360,000	240,000	128,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Wtd. Avg. Exercise Price, Outstanding - beginning balance (in dollars per share)	$ 9.97	$ 9.24
Wtd. Avg. Exercise Price, Awarded (in dollars per share)	$ 8.64	$ 10.70
Wtd. Avg. Exercise Price, Exercised (in dollars per share)	$ 0.00	$ 0.00
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 0.00	$ 9.97
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 9.53	$ 9.97	$ 9.24
2007 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for grant	1,250,000
Total number of shares with respect to which awards may granted to any participant in any calendar year	200,000
Number of shares available for grant	177,821
2007 Stock Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term	10 years	10 years	10 years
Annual vesting percentage	33.30%	33.30%
Award vesting period			3 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - beginning balance (in shares)	738,000	720,500	595,500
Awarded (in shares)	42,500	52,500	125,000
Exercised (in shares)	(2,500)	(10,000)	0
Cancelled (in shares)	0	(25,000)	0
Outstanding - ending balance (in shares)	778,000	738,000	720,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Wtd. Avg. Exercise Price, Outstanding - beginning balance (in dollars per share)	$ 5.79	$ 5.77	$ 4.77
Wtd. Avg. Exercise Price, Awarded (in dollars per share)	$ 8.64	$ 8.10	$ 10.55
Wtd. Avg. Exercise Price, Exercised (in dollars per share)	$ 8.10	$ 6.46	$ 0.00
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 0.00	$ 9.73	$ 0.00
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 5.94	$ 5.79	$ 5.77
2000 and 2004 Stock Plans \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted in previous years that are currently outstanding and exercisable	72,585
Number of options expired during the period	128,105		96,934
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - beginning balance (in shares)	251,365	282,767	529,776
Awarded (in shares)	0	0	0
Exercised (in shares)	(50,675)	(21,975)	(150,075)
Cancelled (in shares)	(128,105)	(9,427)	(96,934)
Outstanding - ending balance (in shares)	72,585	251,365	282,767
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Wtd. Avg. Exercise Price, Outstanding - beginning balance (in dollars per share)	$ 10.96	$ 10.82	$ 10.10
Wtd. Avg. Exercise Price, Awarded (in dollars per share)	$ 0.00	$ 0.00	$ 0.00
Wtd. Avg. Exercise Price, Exercised (in dollars per share)	$ 11.44	$ 9.02	$ 6.85
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 10.50	$ 11.32	$ 13.03
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 11.44	$ 10.96	$ 10.82
Exercisable options (in shares)	72,585	251,365	282,767	529,776
Wtd. Avg. Exercise Price - Exercisable options (in dollars per share)	$ 11.44	$ 10.96	$ 10.82	$ 10.10

Share-Based Compensation Arrangement By Share-Based Payment Award, Award Annual Vesting Percentage

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Share-Based Compensation Arrangement By Share-Based Payment Award Expiration Period

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Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Granted Per Employee

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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Gross number of share options (or share units) granted during the period.

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The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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The number of exercisable share options (fully vested and expected to vest) that may be converted as of the balance sheet date.

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As of the balance sheet date, the weighted-average exercise price (at which grantees can acquire the shares reserved for issuance) for exercisable stock options that are fully vested or expected to vest.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

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Number of share options (or share units) exercised during the current period.

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