Derivative Instruments - Notional Amounts Outstanding under Foreign Currency Contracts - Notional Amount of Buy Currency (Details) - Not Designated as Hedging Instrument - Long € in Thousands, ₩ in Thousands, ¥ in Thousands, £ in Thousands, SGD in Thousands, $ in Thousands	Sep. 30, 2017 SGD	Sep. 30, 2017 KRW (₩)	Sep. 30, 2017 JPY (¥)	Sep. 30, 2017 EUR (€)	Sep. 30, 2017 GBP (£)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 SGD	Sep. 30, 2016 KRW (₩)	Sep. 30, 2016 JPY (¥)	Sep. 30, 2016 EUR (€)	Sep. 30, 2016 GBP (£)	Sep. 30, 2016 USD ($)
Foreign Currency Contract, Buy Japanese Yen, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount | ¥			¥ 391,500
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2017
Derivative [Line Items]
Notional Amount						$ 1,074
Foreign Currency Contract, Buy Korean Won, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount | ₩		₩ 3,230,100
Foreign Currency Contract, Buy United States Dollar, Sell Chinese Yuan, Maturing October 2017
Derivative [Line Items]
Notional Amount						6,294
Foreign Currency Contract, Buy Euro, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount | €				€ 13,700
Foreign Currency Contract, Buy British Pound, Sell Norwegian Krone, Maturing October 2017
Derivative [Line Items]
Notional Amount | £					£ 188
Foreign Currency Contract, Buy Singapore Dollar, Sell United States Dollar, Maturing October 2017
Derivative [Line Items]
Notional Amount | SGD	SGD 700
Foreign Currency Contract, Buy United States Dollar, Sell Israeli Shekel, Maturing October 2017
Derivative [Line Items]
Notional Amount						226
Foreign Currency Contract, Buy United States Dollar, Sell Swiss Franc, Maturing October 2017
Derivative [Line Items]
Notional Amount						$ 3,600
Foreign Currency Contract, Buy Euro, Sell British Pound, Maturing October 2017
Derivative [Line Items]
Notional Amount | €				€ 19,200
Foreign Currency Contract, Buy British Pound, Sell Swedish Krona, Maturing October 2016
Derivative [Line Items]
Notional Amount | £											£ 190
Foreign Currency Contract, Buy Japanese Yen, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount | ¥									¥ 124,000
Foreign Currency Contract, Buy United States Dollar, Sell British Pound, Maturing October 2016
Derivative [Line Items]
Notional Amount												$ 6,107
Foreign Currency Contract, Buy Euro, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount | €										€ 13,300
Foreign Currency Contract, Buy United States Dollar, Sell Chinese Yuan, Maturing October 2016
Derivative [Line Items]
Notional Amount												5,815
Foreign Currency Contract, Buy Korean Won, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount | ₩								₩ 2,488,000
Foreign Currency Contract, Buy Euro, Sell British Pound, Maturing October 2016
Derivative [Line Items]
Notional Amount | €										€ 7,482
Foreign Currency Contract, Buy United States Dollar, Sell Israeli Shekel, Maturing October 2016
Derivative [Line Items]
Notional Amount												311
Foreign Currency Contract, Buy Singapore Dollar, Sell United States Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount | SGD							SGD 360
Foreign Currency Contract, Buy United States Dollar, Sell Taiwanese Dollar, Maturing October 2016
Derivative [Line Items]
Notional Amount												$ 210
Foreign Currency Contract, Buy British Pound, Sell Norwegian Krone, Maturing October 2016
Derivative [Line Items]
Notional Amount | £											£ 171