Shareholders' Equity - Stock Plan Terms and Stock Options Activity (Details) (USD $)	12 Months Ended
May 03, 2014	Apr. 27, 2013	Apr. 28, 2012	Apr. 30, 2011
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	476,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Awarded (in shares)	120,000	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)	360,000	240,000	128,000
Awarded (in shares)	120,000	120,000	128,000
Exercised (in shares)	(59,999)	0	0
Cancelled (in shares)	0	0	(16,000)
Outstanding - ending balance (in shares)	420,001	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)	$ 9.53	$ 9.97	$ 9.24
Wtd. Avg. Exercise Price, Awarded (in dollars per share)	$ 17.27	$ 8.64	$ 10.70
Wtd. Avg. Exercise Price, Exercised (in dollars per share)	$ 9.50	$ 0.00	$ 0.00
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 0.00	$ 0.00	$ 9.97
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 11.74	$ 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	108,321
2007 Stock Plan \| Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award term	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)	778,000	738,000	720,500
Awarded (in shares)	42,500	42,500	52,500
Exercised (in shares)	(648,141)	(2,500)	(10,000)
Cancelled (in shares)	0	0	(25,000)
Outstanding - ending balance (in shares)	172,359	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)	$ 5.94	$ 5.79	$ 5.77
Wtd. Avg. Exercise Price, Awarded (in dollars per share)	$ 17.27	$ 8.64	$ 8.10
Wtd. Avg. Exercise Price, Exercised (in dollars per share)	$ 5.60	$ 8.10	$ 6.46
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 0.00	$ 0.00	$ 9.73
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 10.02	$ 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		0
Number of options expired during the period	1,410	128,105		96,934
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding - beginning balance (in shares)	72,585	251,365	282,767
Awarded (in shares)	0	0	0
Exercised (in shares)	(71,175)	(50,675)	(21,975)
Cancelled (in shares)	(1,410)	(128,105)	(9,427)
Outstanding - ending balance (in shares)	0	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)	$ 11.44	$ 10.96	$ 10.82
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	$ 11.44	$ 9.02
Wtd. Avg. Exercise Price, Cancelled (in dollars per share)	$ 11.44	$ 10.50	$ 11.32
Wtd. Avg. Exercise Price, Outstanding - ending balance (in dollars per share)	$ 0.00	$ 11.44	$ 10.96	$ 10.82
Exercisable options (in shares)		72,585	251,365	282,767
Wtd. Avg. Exercise Price - Exercisable options (in dollars per share)	$ 0.00	$ 11.44	$ 10.96	$ 10.82

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

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- Definition

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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Period from grant date that an equity-based award expires, 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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- Definition

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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- Definition

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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Number of options outstanding, including both vested and non-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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- Definition

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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- Definition

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 per share amount at which grantees can acquire shares of common stock by exercise of options.

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

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