Description Of Business And Basis Of Presentation Fiscal Period (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Mar. 31, 2013	Mar. 31, 2012
Fiscal Period
Current and prior years fiscal period (in weeks)			39	39	52	52
Current and prior years fiscal quarter period (in weeks)	13	13
Minimum
Fiscal Period
Fiscal year (in weeks)					52
Maximum
Fiscal Period
Fiscal year (in weeks)					53