Discontinued operations - Discontinued operations results of operations (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2015	Mar. 31, 2014
Revenue	$ 8,948	$ 8,007	$ 17,250	$ 15,236
Cost of operations	6,789	6,185	12,746	11,238
Operating profit	2,159	1,822	4,504	3,998
Interest expense	(620)	(310)	(1,065)	(599)
Provision for income taxes	541	586	1,263	1,332
Income from discontinued operations	516	787	2,179	1,961
Patriot Transportation
Revenue	10,083	31,900	41,800	63,491
Cost of operations	9,230	30,575	38,195	60,218
Operating profit	853	1,325	3,605	3,273
Interest expense	(7)	(35)	(33)	(58)
Income before income taxes	846	1,290	3,572	3,215
Provision for income taxes	330	503	1,393	1,254
Income from discontinued operations	$ 516	$ 787	$ 2,179	$ 1,961