Derivative Financial Instruments Derivative Financial Instruments (Notional Amounts of Outstanding Forward Contracts (Details) - Foreign Exchange Forward [Member] - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016
Derivative [Line Items]
Derivative, Notional Amount	$ 318,519	$ 249,534
Canadian/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	12,809	14,685
Euro/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	244,000	174,120
Israeli Sheqel/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	8,820	7,271
Japanese Yen/Euro
Derivative [Line Items]
Derivative, Notional Amount	17,694	32,782
Japanese Yen/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	3,198	6,716
Swiss Franc / Euro
Derivative [Line Items]
Derivative, Notional Amount	7,157	0
SEK / U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	4,627	3,852
Chinese Yuan offshore / Euro
Derivative [Line Items]
Derivative, Notional Amount	10,423	0
Singapore Dollar / U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	1,186	1,448
All other
Derivative [Line Items]
Derivative, Notional Amount	8,605	8,660
Designated as Hedging Instrument [Member]
Derivative [Line Items]
Derivative, Notional Amount	101,597	39,059
Designated as Hedging Instrument [Member] | Euro/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	64,831	26,181
Designated as Hedging Instrument [Member] | Japanese Yen/U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	22,675	8,800
Designated as Hedging Instrument [Member] | SEK / U.S. Dollar
Derivative [Line Items]
Derivative, Notional Amount	$ 14,091	$ 4,078