Credit Facility (Details) (Line of credit, Senior secured credit facility, USD $) In Millions, unless otherwise specified	0 Months Ended	1 Months Ended	0 Months Ended				0 Months Ended
	Dec. 05, 2011	Dec. 31, 2012	Dec. 05, 2011 Revolving credit facility	Mar. 29, 2013 Revolving credit facility	Feb. 25, 2013 Revolving credit facility	May 01, 2012 Revolving credit facility	Dec. 05, 2011 Revolving credit facility Percent per annum in excess of LIBOR	Dec. 05, 2011 Revolving credit facility Percent per annum in excess of base rate	Dec. 05, 2011 Revolving credit facility Base rate, percent in excess of Federal Funds rate	Dec. 05, 2011 Revolving credit facility Base rate, percent in excess of LIBOR	Mar. 29, 2013 Letter of credit	May 01, 2012 Letter of credit	Dec. 05, 2011 Letter of credit
Credit facility:
Term of credit facility	5 years
Maximum borrowing capacity			$ 35.0	$ 23.0	$ 25.0	$ 40.0					$ 2.0	$ 10.0	$ 10.0
Description of variable rate basis							LIBOR	base rate	Federal Funds	LIBOR
Duration of initial credit facility term in which the Company can increase maximum borrowing capacity			18 months
Increase in maximum borrowing capacity						5.0
Decrease in maximum borrowing capacity					15.0
Basis spread on variable rate							2.50%	1.75%	0.50%	1.00%
Unused line fees percentage			0.40%
Repayments of debt		15.7
Interest paid		$ 0.4