Geographic Information (Schedule of Revenues from External Customers by Geographical Areas) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	$ 661,858	$ 647,814	$ 640,867
United States
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	474,038	365,085	374,453
Canada
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	101,191	137,684	113,391
Middle East and Africa
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	40,557	84,330	61,618
Europe (including former Soviet Union)
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	23,567	34,920	24,092
Far East
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	12,026	15,127	35,388
Mexico, Central and South America
Revenues From External Customers And Long Lived Assets [Line Items]
Total revenues	$ 10,479	$ 10,668	$ 31,925