Commitment and Contingencies (Details) (USD $)	0 Months Ended	3 Months Ended
	Feb. 27, 2014 item sqft	Mar. 31, 2014	Apr. 02, 2014
Commitment and contingencies
Lease term	121 months
Area of land leased (in square feet)	63,922
Number of separate and successive extended lease term period	2
Extension of lease term	5 years
Base rent (as a percent)	95.00%
Number of months prior to which termination notification is to be provided		9 months
Total value of lease		$ 16,100,000
Tenant improvement allowance		4,000,000
Number of months in which base rent and other direct expenses will be abated		13 months
Construction allowance		4,200,000
Surety bond, notional amount			$ 6,100,000