Significant Accounting Policies (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2012 week	Dec. 31, 2012 week	Dec. 31, 2011 week
Basis of Presentation and Principles of Consolidation
Number of weeks in fiscal year, low end of the range	52
Number of weeks in fiscal year, high end of the range	53
Number of weeks in fiscal year		52	52
Number of weeks in each fiscal quarter for 52-week fiscal year	13