Discontinued operations - Discontinued operations results of operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue	$ 8,497	$ 7,679	$ 25,747	$ 22,915
Cost of operations	4,608	4,816	17,354	16,054
Operating profit	3,889	2,863	8,393	6,861
Interest expense	(459)	(410)	(1,524)	(1,009)
Provision for income taxes	1,308	1,121	2,572	2,453
Income from discontinued operations	0	1,731	2,179	3,692
Patriot Transportation
Revenue	0	33,569	41,800	97,060
Cost of operations	0	30,702	38,195	90,920
Operating profit	0	2,867	3,605	6,140
Interest expense	0	(28)	(33)	(86)
Income before income taxes	0	2,839	3,572	6,054
Provision for income taxes	0	1,108	1,393	2,362
Income from discontinued operations	$ 0	$ 1,731	$ 2,179	$ 3,692