Derivative Financial Instruments (Schedule Of Notional Amounts Of Outstanding Derivative Positions) (Details) - Mar. 31, 2017 € in Millions, £ in Millions, SGD in Millions, NOK in Millions, NGN in Millions, MYR in Millions, CAD in Millions, BRL in Millions, AUD in Millions, $ in Millions	NOK	BRL	USD ($)	EUR (€)	GBP (£)	NGN	CAD	SGD	AUD	MYR
Foreign Exchange Forward | Australian dollar | Notional Amount Bought
Derivative
Derivative, notional amount			$ 180.3						AUD 236.6
Foreign Exchange Forward | Brazilian real | Notional Amount Bought
Derivative
Derivative, notional amount		BRL 571.9	179.8
Foreign Exchange Forward | British pound | Notional Amount Bought
Derivative
Derivative, notional amount			273.7		£ 219.4
Foreign Exchange Forward | Canadian dollar | Notional Amount Sold
Derivative
Derivative, notional amount			129.8				CAD 172.7
Foreign Exchange Forward | Euro | Notional Amount Bought
Derivative
Derivative, notional amount			966.2	€ 895.0
Foreign Exchange Forward | Malaysian ringgit | Notional Amount Bought
Derivative
Derivative, notional amount			52.7							MYR 233.2
Foreign Exchange Forward | Nigerian naira | Notional Amount Sold
Derivative
Derivative, notional amount			17.2			NGN 5,341.3
Foreign Exchange Forward | Norwegian krone | Notional Amount Bought
Derivative
Derivative, notional amount	NOK 919.9		107.7
Foreign Exchange Forward | Singapore dollar | Notional Amount Bought
Derivative
Derivative, notional amount			92.3					SGD 129.0
Foreign Exchange Forward | U.S. dollar | Notional Amount Sold
Derivative
Derivative, notional amount			1,741.0
Long-term – Derivative financial instruments – Synthetic Bonds – Embedded Derivatives | Brazilian real | Notional Amount Sold
Derivative
Derivative, notional amount		BRL 54.4	17.1
Long-term – Derivative financial instruments – Synthetic Bonds – Embedded Derivatives | Euro | Notional Amount Sold
Derivative
Derivative, notional amount			25.4	€ 23.7
Long-term – Derivative financial instruments – Synthetic Bonds – Embedded Derivatives | Norwegian krone | Notional Amount Sold
Derivative
Derivative, notional amount	NOK 240.2		27.9
Long-term – Derivative financial instruments – Synthetic Bonds – Embedded Derivatives | U.S. dollar | Notional Amount Bought
Derivative
Derivative, notional amount			$ 68.7