Note 10 - Change In Accounting Principle - Statement of Operations (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended					6 Months Ended		9 Months Ended
	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Sep. 30, 2014
Scenario, Previously Reported [Member]
Statement of Operations:
Operations and maintenance	$ 12,176	$ 12,140	$ 12,863	$ 11,629	$ 13,062	$ 24,316	$ 24,691	$ 37,554
Depreciation and amortization	10,277	10,671	10,671			20,948		33,274
Operating income	5,284	3,591	5,419	4,257	(1,043)	8,875	3,214	8,633
Income before income taxes	4,365	2,009	4,534	1,366	(2,183)	6,374	(817)	3,717
Income tax expense	1,905	893	1,817	644	(594)	2,798	50	1,867
Net income and Comprehensive income	$ 2,460	$ 1,116	$ 2,717	$ 722	$ (1,589)	$ 3,576	$ (867)	$ 1,850
Average shares outstanding (basic) (in shares)	10,435	10,395	10,357	10,346	10,339	10,423	10,343	10,350
Basic earnings per share (in dollars per share)	$ 0.24	$ 0.11	$ 0.26	$ 0.07	$ (0.15)	$ 0.34	$ (0.08)	$ 0.18
Average shares outstanding (diluted) (in shares)	10,516	10,516	10,476	10,478	10,399	10,524	10,343	10,482
Diluted earnings per share (in dollars per share)	$ 0.23	$ 0.11	$ 0.26	$ 0.07	$ (0.15)	$ 0.34	$ (0.08)	$ 0.18
Restatement Adjustment [Member]
Statement of Operations:
Operations and maintenance	$ (700)	$ (1,066)	$ (2,214)	$ 650	$ 9	$ (1,766)	$ 659	$ (1,555)
Depreciation and amortization	170	131	121			301		121
Operating income	530	935	2,093	(650)	(9)	1,465	(659)	1,434
Income before income taxes	530	935	2,093	(650)	(9)	1,465	(659)	1,434
Income tax expense	220	416	804	(250)	(3)	636	(253)	551
Net income and Comprehensive income	$ 310	$ 519	$ 1,289	$ (400)	$ (6)	$ 829	$ (406)	$ 883
Basic earnings per share (in dollars per share)	$ 0.03	$ 0.05	$ 0.13	$ (0.04)	$ 0	$ 0.08	$ (0.04)	$ 0.09
Diluted earnings per share (in dollars per share)	$ 0.03	$ 0.05	$ 0.12	$ (0.04)	$ 0	$ 0.08	$ (0.04)	$ 0.08
Operations and maintenance	$ 11,476	$ 11,074	$ 10,649	$ 12,279	$ 13,071	$ 22,550	$ 25,350	$ 35,999
Depreciation and amortization	10,447	10,802	10,792			21,249		33,395
Operating income	5,814	4,526	7,512	3,607	(1,052)	10,340	2,555	10,067
Income before income taxes	4,895	2,944	6,627	716	(2,192)	7,839	(1,476)	5,151
Income tax expense	2,125	1,309	2,621	394	(597)	3,434	(203)	2,418
Net income and Comprehensive income	$ 2,770	$ 1,635	$ 4,006	$ 322	$ (1,595)	$ 4,405	$ (1,273)	$ 2,733
Average shares outstanding (basic) (in shares)			10,357					10,350
Basic earnings per share (in dollars per share)	$ 0.27	$ 0.16	$ 0.39	$ 0.03	$ (0.15)	$ 0.42	$ (0.12)	$ 0.26
Average shares outstanding (diluted) (in shares)			10,476					10,482
Diluted earnings per share (in dollars per share)	$ 0.26	$ 0.16	$ 0.38	$ 0.03	$ (0.15)	$ 0.42	$ (0.12)	$ 0.26