Derivative Instruments and Hedging Activities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Sep. 30, 2013
Forward starting swap
Derivative instruments and hedging activities
Notional Principal outstanding derivative instruments	$ 56,000
Instruments designated as accounting hedges: | Foreign currency forwards
Derivative instruments and hedging activities
Notional Principal outstanding derivative instruments	395,739	361,337
Instruments designated as accounting hedges: | Forward starting swap
Derivative instruments and hedging activities
Notional Principal outstanding derivative instruments		58,415
Instruments not designated as accounting hedges: | Foreign currency forwards
Derivative instruments and hedging activities
Notional Principal outstanding derivative instruments	885	2,697
Instruments not designated as accounting hedges: | Forward starting swap
Derivative instruments and hedging activities
Notional Principal outstanding derivative instruments	$ 55,962