Operating Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 259,700	$ 268,114	$ 529,057	$ 540,775
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	210,379	222,341	427,865	446,376
Mexico
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	41,414	35,316	86,368	73,658
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	3,075	2,955	6,660	5,928
U.K.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 4,832	$ 7,502	$ 8,164	$ 14,813