Debt (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended										12 Months Ended			12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2011 sqft	Jun. 01, 2004 sqft	Dec. 31, 2012 Land owned [Member]	Dec. 31, 2011 Land owned [Member]	Dec. 31, 2012 Building [Member]	Dec. 31, 2011 Building [Member]	Dec. 31, 2012 April 26, 2014 [Member]	Dec. 31, 2011 April 26, 2014 [Member]	Dec. 31, 2012 December 20, 2018 [Member]	Dec. 31, 2011 December 20, 2018 [Member]	Dec. 20, 2011 December 20, 2018 [Member]	Dec. 31, 2012 Revolving credit facility [Member]	Oct. 26, 2012 Revolving credit facility [Member]	Dec. 31, 2011 Revolving credit facility [Member]	Dec. 31, 2012 Fixed rate notes [Member]	Dec. 31, 2011 Fixed rate notes [Member]	Dec. 31, 2012 Fixed rate notes [Member] April 26, 2014 [Member]	Dec. 31, 2012 Fixed rate notes [Member] December 20, 2018 [Member]	Dec. 31, 2012 Seven year fixed rate notes [Member]	Dec. 20, 2011 Seven year fixed rate notes [Member]	Dec. 31, 2012 Maximum [Member]	Dec. 31, 2012 Maximum [Member] Revolving credit facility [Member]	Dec. 31, 2012 Maximum [Member] Seven year fixed rate notes [Member] October 26th Fixed rate debt [Member]	Dec. 31, 2012 Minimum [Member]	Dec. 31, 2012 Minimum [Member] October 26th Fixed rate debt [Member]	Dec. 31, 2012 Minimum [Member] Revolving credit facility [Member]
Line of Credit Facility [Line Items]
Borrowings															$ 100,000
Applicable margin added to the interest rate																							3.50%			2.50%
Fixed rate notes payable																	40,000				20,000
Other notes payable	11,429								11,429	17,143
Notes Payable											20,000	20,000										20,000
Applicable margin added to the interest rate post amendment														1.50%										2.25%				1.25%
Expiration date																				Dec. 20, 2018
Senior notes maturity period											7 years
Unamortized balance														2,012		1,761	157	290
Percentage of fixed interest rate bearing											4.64%		4.64%						4.89%
Fair value					520	854	1,930	1,107
Percentage of fixed interest rate bearing pre amendment																											5.39%
Percentage of fixed interest rate bearing post amendment																									4.89%
Line of credit LIBOR rate														0.25%
Annual principal payment of fixed rate notes											4,000								5,714
Debt (Textual) [Abstract]
Fixed charge coverage ratio current required minimum	1.00
Potential to expand credit facility under credit agreement	35,000
Lease of land and building			75,000	110,000
Aggregate non discounted lease payments over the twenty year term	5,700	3,700
Period of lease agreement	20 years	20 years
Undiscounted annual lease payments	287	185
Amount of credit facility to meet short term cash flow needs	$ 10,000
Method of determining interest rate under revolving credit facility	LIBOR plus an applicable margin