Credit Facilities - Additional Information (Detail) (USD $)	12 Months Ended			12 Months Ended		1 Months Ended		2 Months Ended				12 Months Ended
	Dec. 31, 2013 store	Dec. 31, 2012 store	Dec. 31, 2011 store	Dec. 31, 2013 Minimum	Dec. 31, 2013 Maximum	Jul. 05, 2011 Senior Unsecured Notes Issued July 2011	Dec. 31, 2002 Related Party Property	Nov. 30, 2004 Related Party Property	Dec. 31, 2013 Unsecured Revolving Credit Facility	Dec. 31, 2013 Revolving Credit Agreement	Dec. 31, 2012 Revolving Credit Agreement	Dec. 31, 2013 Revolving Credit Agreement Minimum	Dec. 31, 2013 Revolving Credit Agreement Maximum	Dec. 31, 2013 Revolving Credit Agreement LIBOR Minimum	Dec. 31, 2013 Revolving Credit Agreement LIBOR Maximum
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity									$ 140,000,000
Revolving credit agreement, expiry date	Dec. 13, 2017
Interest rate basis spread														1.00%	1.50%
Line of credit amount outstanding	0									0	0
Commitment fee for unused balance amount												0.15%	0.30%
Notes issued						125,000,000
Debt interest rate						3.75%
Debt instrument, maturity date						Apr. 27, 2018
Payment of Interest, commencement date						Jul. 27, 2011
Annual principal repayment amount						25,000,000
Debt principal amount, commencement date						Apr. 27, 2014
Properties sold	2	3	25				10	11
Borrowings collateralized by the land and buildings							5,000,000	6,800,000
Lease term	15 years						15 years	15 years
Lease renewal option term				1 year	20 years			5 years
Aggregate annual rental							1,227,000	716,000
Interest implicit in the leases							10.10%	9.70%
Industrial development corporation revenue bonds	$ 3,250,000	$ 3,250,000
Weighted-average borrowing rate on bonds	0.25%	0.35%