Operating Segment Information (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 234,366	$ 235,166	$ 268,114	$ 272,661	$ 253,961	$ 224,573	$ 251,980	$ 244,609	$ 1,010,307	$ 975,123	$ 852,798
Long-lived assets	606,661				527,979				606,661	527,979	271,494
U.S. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									822,587	850,946	795,825
Long-lived assets	399,930				317,887				399,930	317,887	240,661
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									150,022	103,273	49,601
Long-lived assets	157,796				155,488				157,796	155,488	22,945
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									12,710	10,712	7,372
Long-lived assets	4,755				10,199				4,755	10,199	7,888
U.K. [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									24,988	10,192	0
Long-lived assets	44,138				44,363				44,138	44,363	0
Other [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 42				$ 42				$ 42	$ 42	$ 0