Long-lived Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	$ 119,070	$ 153,918	$ 192,829
United States
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	108,021	136,617	162,548
Canada
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	7,325	11,911	19,323
Colombia
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	1,747	3,487	9,227
Russian Federation
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	1,461	1,498	1,215
United Kingdom
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	502	391	502
China
Schedule Of Long Lived Assets [Line Items]
Long-lived assets	$ 14	$ 14	$ 14