Derivative Instruments (Foreign Currency Contracts) (Details) - Sep. 30, 2018 - Foreign Exchange Forward - Not Designated as Hedging Instrument € in Millions, ¥ in Millions, £ in Millions, kr in Millions, $ in Millions, $ in Millions, $ in Millions, $ in Millions	SGD ($)	AUD ($)	JPY (¥)	GBP (£)	EUR (€)	CAD ($)	DKK (kr)	USD ($)
Long | Sell US Dollars and Buy Canadian Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract						$ 59.2
Long | Sell Euros and Buy Canadian Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract						$ 15.8
Long | Sell Great British Pounds and Buy Euros
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | €					€ 55.0
Long | Sell Australian Dollars and Buy Great Britain Pounds
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | £				£ 1.2
Long | Sell US Dollars and Buy Great Britain Pounds
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | £				97.7
Long | Sell US Dollars and Buy Singapore Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract	$ 2.1
Long | Sell US Dollars and Buy Euros
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | €					26.9
Long | Sell Japanese Yen and Buy US Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								$ 0.9
Long | Sell US Dollars And Buy Danish Krone
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | kr							kr 62.6
Short | Sell US Dollars and Buy Canadian Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								45.5
Short | Sell Euros and Buy Canadian Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | €					€ 10.4
Short | Sell Great British Pounds and Buy Euros
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | £				£ 49.1
Short | Sell Australian Dollars and Buy Great Britain Pounds
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract		$ 2.2
Short | Sell US Dollars and Buy Great Britain Pounds
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								128.1
Short | Sell US Dollars and Buy Singapore Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								1.5
Short | Sell US Dollars and Buy Euros
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								31.3
Short | Sell Japanese Yen and Buy US Dollars
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract | ¥			¥ 100.0
Short | Sell US Dollars And Buy Danish Krone
Derivative Instruments (Textual) [Abstract]
Amount of foreign currency contract								$ 9.8