Derivative Instruments - Notional Amounts Outstanding under Foreign Currency Contracts - Notional Amount of Sell Currency (Details) - Not Designated as Hedging Instrument - Short ₪ in Thousands, ¥ in Thousands, £ in Thousands, TWD in Thousands, SFr in Thousands, SEK in Thousands, NOK in Thousands, $ in Thousands	Sep. 30, 2017 CHF (SFr)	Sep. 30, 2017 ILS (₪)	Sep. 30, 2017 CNY (¥)	Sep. 30, 2017 NOK	Sep. 30, 2017 GBP (£)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 TWD	Sep. 30, 2016 ILS (₪)	Sep. 30, 2016 CNY (¥)	Sep. 30, 2016 SEK	Sep. 30, 2016 NOK	Sep. 30, 2016 GBP (£)	Sep. 30, 2016 USD ($)
Foreign Currency Contract, Buy Japanese Yen, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount						$ 3,473
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2017
Derivative [Line Items]
Notional Amount | £					£ 800
Foreign Currency Contract, Buy Korean Won, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount						2,833
Foreign Currency Contract, Buy United States Dollar, Sell Chinese Yuan, Maturing October 2017
Derivative [Line Items]
Notional Amount | ¥			¥ 41,800
Foreign Currency Contract, Buy Euro, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount						16,167
Foreign Currency Contract, Buy British Pound, Sell Norwegian Krone, Maturing October 2017
Derivative [Line Items]
Notional Amount | NOK				NOK 2,000
Foreign Currency Contract, Buy Singapore Dollar, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount						$ 515
Foreign Currency Contract, Buy United States Dollar, Sell Israeli Shekel, Maturing October 2017
Derivative [Line Items]
Notional Amount | ₪		₪ 800
Foreign Currency Contract, Buy United States Dollar, Sell Swiss Franc, Maturing October 2017
Derivative [Line Items]
Notional Amount | SFr	SFr 3,500
Foreign Currency Contract, Buy Euro, Sell British Pound, Maturing October 2017
Derivative [Line Items]
Notional Amount | £					£ 16,888
Foreign Currency Contract, Buy British Pound, Sell Swedish Krona, Maturing October 2016
Derivative [Line Items]
Notional Amount | SEK										SEK 2,100
Foreign Currency Contract, Buy Japanese Yen, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount													$ 1,229
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2016
Derivative [Line Items]
Notional Amount | £												£ 4,710
Foreign Currency Contract, Buy Euro, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount													14,976
Foreign Currency Contract, Buy United States Dollar, Sell Chinese Yuan, Maturing October 2016
Derivative [Line Items]
Notional Amount | ¥									¥ 39,000
Foreign Currency Contract, Buy Korean Won, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount													2,255
Foreign Currency Contract, Buy Euro, Sell British Pound, Maturing October 2016
Derivative [Line Items]
Notional Amount | £												£ 6,500
Foreign Currency Contract, Buy United States Dollar, Sell Israeli Shekel, Maturing October 2016
Derivative [Line Items]
Notional Amount | ₪								₪ 1,169
Foreign Currency Contract, Buy Singapore Dollar, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount													$ 265
Foreign Currency Contract, Buy United States Dollar, Sell Taiwanese Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount | TWD							TWD 6,600
Foreign Currency Contract, Buy British Pound, Sell Norwegian Krone, Maturing October 2016
Derivative [Line Items]
Notional Amount | NOK											NOK 1,800