Quarterly Financial Data (Unaudited) - Summary of Unaudited Quarterly Results (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Quarterly Financial Information Disclosure [Abstract]
Total revenue	$ 13,843	$ 13,959	$ 12,210	$ 11,916	$ 14,297	$ 14,289	$ 13,695	$ 13,851	$ 56,132	$ 51,928	$ 52,756
Operating income from continuing operations	4,638	4,793	3,689	3,222	5,576	4,238	4,129	4,877	18,820	16,342	15,523
Income from continuing operations	2,854	3,174	1,946	2,155	3,733	3,178	3,420	4,248	14,579	10,129	10,925
Income (loss) from discontinued operations	(114)	(112)	(223)	551	(47)	(47)	682		588	102	(29,431)
Net income	$ 2,740	$ 3,062	$ 1,723	$ 2,706	$ 3,686	$ 3,131	$ 4,102	$ 4,248	$ 15,167	$ 10,231	$ (18,506)
Basic income (loss) per share(1):
Continuing operations	$ 0.17	$ 0.18	$ 0.11	$ 0.12	$ 0.26	$ 0.22	$ 0.23	$ 0.29	$ 1.01	$ 0.58	$ 0.63
Discontinued operations	$ (0.01)	$ (0.01)	$ (0.01)	$ 0.03	$ 0.00	$ 0.00	$ 0.05	$ 0.00	$ 0.04	$ 0.01	$ (1.69)
Net income	$ 0.16	$ 0.17	$ 0.10	$ 0.15	$ 0.26	$ 0.22	$ 0.28	$ 0.29	$ 1.05	$ 0.59	$ (1.06)
Diluted income (loss) per share(1):
Continuing operations	$ 0.17	$ 0.18	$ 0.11	$ 0.12	$ 0.26	$ 0.22	$ 0.23	$ 0.29	$ 0.99	$ 0.58	$ 0.63
Discontinued operations	$ (0.01)	$ (0.01)	$ (0.01)	$ 0.03	$ 0.00	$ 0.00	$ 0.05	$ 0.00	$ 0.04	$ 0.01	$ (1.69)
Net income	$ 0.16	$ 0.17	$ 0.10	$ 0.15	$ 0.26	$ 0.21	$ 0.28	$ 0.29	$ 1.03	$ 0.59	$ (1.06)