Commitments and Contingencies (Details) $ in Thousands					3 Months Ended	12 Months Ended	15 Months Ended
	Mar. 01, 2017 USD ($) ft²	Feb. 27, 2017 USD ($) shares	May 04, 2016 USD ($) a ft²	Jan. 25, 2016 USD ($) a	Feb. 28, 2017 USD ($) shares	Nov. 30, 2016 USD ($) shares	Feb. 28, 2017 USD ($) shares	Dec. 23, 2016 USD ($) a	May 11, 2016 USD ($)	Mar. 23, 2016 USD ($) a
Commitments and Contingencies
Stock repurchased					$ 1,474
Subsequent events
Commitments and Contingencies
Area Of Building | ft²	100,000
Agreement to sell
Commitments and Contingencies
Purchase obligations				$ 7,700
Purchase Option Term				3 months
Agreement Term of Extension				3 years
Agreement Extension Fee				$ 80
Number of acres to be sold | a								67
Sale price								$ 10,250
Number of acres | a				280				268
Common Stock
Commitments and Contingencies
Stock repurchase program, authorized amount					$ 5,000		$ 5,000		$ 5,000
Stock repurchased (in shares) | shares		28,000			47,173	105,000	152,173
Stock repurchased		$ 880			$ 1,474	$ 3,354	$ 4,828
Common stock repurchase program, remaining authorized amount					172		172
Obligations For Investments In Real Estate Assets [Member]
Commitments and Contingencies
Purchase obligations					$ 2,516		$ 2,516
East Allen Township Northampton County PA Site [Member] | Obligations For Investments In Real Estate Assets [Member]
Commitments and Contingencies
Purchase obligations										$ 6,200
Number of acres | a										31
East Allen Township Northampton County PA Site [Member] | Obligations For Investments In Real Estate Assets [Member] | Subsequent events
Commitments and Contingencies
Purchase obligations	$ 5,600
Upper Macungie Township Lehigh County PA Site [Member] | Obligations For Investments In Real Estate Assets [Member]
Commitments and Contingencies
Purchase obligations			$ 1,800
Number of acres | a			14
Area Of Building | ft²			134,000