Fair Value of Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Minimum
Fair Value Measurements
Performance risk for derivative contracts as a percentage of unadjusted liabilities			11.00%
Maximum
Fair Value Measurements
Performance risk for derivative contracts as a percentage of unadjusted liabilities			24.10%
Weighted average
Fair Value Measurements
Performance risk for derivative contracts as a percentage of unadjusted liabilities			17.70%
Cross currency swaps
Level 3 activity
Beginning balance:	$ (25,877)	$ (11,267)	$ (24,862)	$ (11,126)
Unrealized gain (loss) on cross hedging instruments	19,750	(7,322)	18,735	(7,463)
Ending balance:	$ (6,127)	$ (18,589)	$ (6,127)	$ (18,589)