Fair Value Measurements - Recurring Fair Value Measurements (Details) - Recurring [Member] - USD ($) $ in Thousands	Sep. 30, 2015	Sep. 30, 2014
Financial assets that are measured at fair value on a recurring basis
Holding period adjustment	$ 4
Contingent consideration	(2,601)	$ (3,758)
Net financial assets (liabilities)	11,572	(186)
Foreign currency forward [Member] | Non-designated derivatives [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	10,681	1,152
Foreign currency forward [Member] | Designated as hedging instrument [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	3,488	2,420
Convertible notes hedges [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	10,505	36,994
Convertible notes embedded derivative [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative liability	(10,505)	(36,994)
Level 1 [Member]
Financial assets that are measured at fair value on a recurring basis
Holding period adjustment	0
Contingent consideration	0	0
Net financial assets (liabilities)	0	0
Level 1 [Member] | Foreign currency forward [Member] | Non-designated derivatives [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 1 [Member] | Foreign currency forward [Member] | Designated as hedging instrument [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 1 [Member] | Convertible notes hedges [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 1 [Member] | Convertible notes embedded derivative [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative liability	0	0
Level 2 [Member]
Financial assets that are measured at fair value on a recurring basis
Holding period adjustment	4
Contingent consideration	0	0
Net financial assets (liabilities)	14,173	3,572
Level 2 [Member] | Foreign currency forward [Member] | Non-designated derivatives [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	10,681	1,152
Level 2 [Member] | Foreign currency forward [Member] | Designated as hedging instrument [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	3,488	2,420
Level 2 [Member] | Convertible notes hedges [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	10,505	36,994
Level 2 [Member] | Convertible notes embedded derivative [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative liability	(10,505)	(36,994)
Level 3 [Member]
Financial assets that are measured at fair value on a recurring basis
Holding period adjustment	0
Contingent consideration	(2,601)	(3,758)
Net financial assets (liabilities)	(2,601)	(3,758)
Level 3 [Member] | Foreign currency forward [Member] | Non-designated derivatives [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 3 [Member] | Foreign currency forward [Member] | Designated as hedging instrument [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 3 [Member] | Convertible notes hedges [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative asset	0	0
Level 3 [Member] | Convertible notes embedded derivative [Member]
Financial assets that are measured at fair value on a recurring basis
Derivative liability	$ 0	$ 0