Long-Term Debt (Narrative) (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended			1 Months Ended
	Aug. 31, 2011	Apr. 30, 2012 Revolving Credit Facility [Member]	Mar. 28, 2012 Revolving Credit Facility [Member]	Aug. 31, 2011 Revised Unsecured Senior Credit Facility [Member]	Aug. 31, 2011 Revised Unsecured Senior Credit Facility [Member] Revolving Credit Facility [Member]	Aug. 31, 2011 Revised Unsecured Senior Credit Facility [Member] Term Loan [Member]	Aug. 31, 2011 Unsecured Senior Credit Facility [Member]	Mar. 28, 2012 LIBOR Rate [Member]	Aug. 31, 2011 LIBOR Rate [Member] Revised Unsecured Senior Credit Facility [Member] Revolving Credit Facility [Member]	Aug. 31, 2011 LIBOR Rate [Member] Revised Unsecured Senior Credit Facility [Member] Term Loan [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 500			$ 400
Line of credit facility, expiration date				August 2016
Line of credit facility, current borrowing capacity					250	250
Basis spread on variable rate					1.63%	1.63%			2.50%	2.50%
Reference rate for variable rate								0.24%
Line of credit facility, remaining borrowing capacity			250
Amount borrowed against the revolver		40
Debt issuance cost	$ 0.4