Shareholders' Equity - RSA and RSU Activity (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended													12 Months Ended									12 Months Ended				12 Months Ended						1 Months Ended	12 Months Ended
	May 03, 2014	Apr. 27, 2013	Apr. 28, 2012	May 03, 2014 2010 Stock Plan	Apr. 27, 2013 2010 Stock Plan	Apr. 28, 2012 2010 Stock Plan	May 03, 2014 2010 Stock Plan RSAs	Apr. 27, 2013 2010 Stock Plan RSAs	Apr. 28, 2012 2010 Stock Plan RSAs	Apr. 27, 2013 2010 Stock Plan RSAs Cliff vesting	Apr. 30, 2011 2010 Stock Plan RSAs Cliff vesting	May 03, 2014 2010 Stock Plan RSAs Cliff vesting	May 03, 2014 2010 Stock Plan RSAs Cliff vesting Target	Apr. 27, 2013 2010 Stock Plan Bonus in Lieu of Dividends	May 03, 2014 2010 Stock Plan Tandem Cash Award	Apr. 27, 2013 2010 Stock Plan Tandem Cash Award	May 03, 2014 2010 Stock Plan RSUs	Apr. 27, 2013 2010 Stock Plan RSUs	Apr. 28, 2012 2010 Stock Plan RSUs	Apr. 27, 2013 2010 Stock Plan RSUs Equal annual installments	Apr. 30, 2011 2010 Stock Plan RSUs Equal annual installments	May 03, 2014 2010 Stock Plan RSUs Equal annual installments	Apr. 27, 2013 2010 Stock Plan RSAs and RSUs One-third per year, beginning in FY 2015, performance based	Apr. 28, 2012 2010 Stock Plan RSAs and RSUs One-third per year, beginning in FY 2015, performance based	May 03, 2014 2010 Stock Plan RSAs and RSUs One-third per year, beginning in FY 2015, performance based	May 03, 2014 2010 Stock Plan RSAs and RSUs One-third per year, beginning in FY 2015, performance based Target	May 03, 2014 2007 Stock Plan	Apr. 27, 2013 2007 Stock Plan	Apr. 28, 2012 2007 Stock Plan	May 03, 2014 2007 Stock Plan RSAs	Apr. 27, 2013 2007 Stock Plan RSAs	Apr. 28, 2012 2007 Stock Plan RSAs	Apr. 30, 2007 2007 Stock Plan RSUs	May 03, 2014 2007 Stock Plan RSUs	Apr. 30, 2007 2007 Stock Plan Converted from RSAs to RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Annual vesting percentage									33.30%														33.30%
Historic multiple of EBITDA, used to calculate internal enterprise value for determining size of awards									7.5
Restriction period for awards														5 years				5 years
Maximum percentage of RSA award that could be the value of Tandem Cash Award																40.00%
Compensation expense	$ 3.3	$ 3.3	$ 4.0	$ 2.6	$ 2.5	$ 2.9	$ 1.5	$ 1.5	$ 1.4						$ 3.9	$ 2.1	$ 0.3	$ 0.5	$ 0.9								$ 0.7	$ 0.8	$ 1.1	$ 0.4	$ 0.2	$ 0.3
Number of shares converted from RSAs to RSUs																															0				225,000
Number of day after termination that awards will be issued and delivered																																	30 days
Number of shares that have been delivered to date																														27,000	27,000	28,860		0
Award vesting period										5 years										5 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested and unissued - beginning balance (in shares)							700,000	700,000	640,000								120,000	180,000	256,000											0	0	0
Awarded (in shares)							0	0	100,000		600,000						0	0	0		300,000			100,000						27,000	27,000	28,860
Vested (in shares)							0	0	0								(60,000)	(60,000)	(60,000)											(27,000)	(27,000)	(28,860)
Forfeited and cancelled (in shares)							0	0	(40,000)								0	0	(16,000)											0	0	0
Unvested and unissued - ending balance (in shares)							700,000	700,000	700,000								60,000	120,000	180,000											0	0	0
Weighted average value (in dollars per share)											$ 9.70										$ 9.70			$ 8.10
Probable unearned compensation expense												$ 1.3	$ 1.3									$ 0.1			$ 0.3	$ 0.3