Common Stock Purchase Agreement (Details) (Common stock purchase agreement with Aspire Capital Fund, LLC, USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Dec. 28, 2012	Oct. 24, 2011 Y
Common stock purchase agreement with Aspire Capital Fund, LLC
Common Stock Purchase Agreement
Maximum value of shares of common stock Aspire is committed to purchase		$ 20.0
Period over which shares of common stock are committed for issuance (in years)		3
Termination costs incurred	$ 0
Shares of common stock issued pursuant to Purchase Agreement excluding Commitment Shares	100,000
Shares of common stock issued pursuant to Purchase Agreement including Commitment Shares	478,788