Facility Closure Reserves - Additional Information (Detail) (Retail Segment, USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012 Store
Retail Segment
Restructuring Cost and Reserve [Line Items]
Charges related to stores closed	$ 25.3
Total number of under performing stores	15

Facility Closure Reserve Charges Related To Closed Stores

No definition available.

Name:	omx_FacilityClosureReserveChargesRelatedToClosedStores
Namespace Prefix:	omx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration