Discontinued operations - Discontinued operations results of operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenue	$ 9,243	$ 8,497	$ 27,681	$ 25,747
Cost of operations	7,277	4,608	15,606	17,354
Interest expense	(392)	(459)	(1,288)	(1,524)
Provision for income taxes	505	1,309	6,573	2,572
Income from discontinued operations	0	0	0	2,179
Patriot Transportation
Revenue	0	0	0	41,800
Cost of operations	0	0	0	38,195
Operating profit	0	0	0	3,605
Interest expense	0	0	0	(33)
Income before income taxes	0	0	0	3,572
Provision for income taxes	0	0	0	1,393
Income from discontinued operations	$ 0	$ 0	$ 0	$ 2,179