Summarized Quarterly Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Summarized Quarterly Data [Abstract]
Net operating revenue	$ 17,745	$ 18,723	$ 17,791	$ 17,569	$ 17,603	$ 18,146	$ 18,002	$ 17,115	$ 71,828	$ 70,866
Earnings from operations	894	1,615	1,695	1,572	984	1,548	977	756	5,776	4,265
Net earnings	$ 624	$ 1,186	$ 1,148	$ 1,133	$ 590	$ 1,423	$ 644	$ 364	$ 4,091	$ 3,021
Basic earnings (loss) per share:
Net earnings (loss)	$ 0.03	$ 0.05	$ 0.05	$ 0.05	$ 0.03	$ 0.06	$ 0.03	$ 0.02	$ 0.17	$ 0.13
Diluted earnings (loss) per share:
Net earnings (loss)	$ 0.03	$ 0.05	$ 0.05	$ 0.05	$ 0.03	$ 0.06	$ 0.03	$ 0.02	$ 0.17	$ 0.13