Derivative Instrument (Notional Table) (Details) - USD ($)		9 Months Ended	12 Months Ended
		Sep. 30, 2015	Dec. 31, 2014
Net Investment Hedging [Member] | CAD
Derivatives Fair Value [Line Items]
Notional Amount Of Nonderivative Instruments			$ 250,000,000
Net Investment Hedging [Member] | GBP
Derivatives Fair Value [Line Items]
Notional Amount Of Nonderivative Instruments			1,050,000,000
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | USD
Derivatives Fair Value [Line Items]
Derivative, Notional Amount		$ 57,000,000	57,000,000
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | CAD
Derivatives Fair Value [Line Items]
Derivative, Notional Amount		72,000,000	58,000,000
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | GBP
Derivatives Fair Value [Line Items]
Derivative, Notional Amount		57,000,000	40,000,000
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member] | CAD
Derivatives Fair Value [Line Items]
Derivative, Notional Amount		1,175,000,000	900,000,000
Notional Amount Of Nonderivative Instruments		250,000,000
Designated as Hedging Instrument [Member] | Net Investment Hedging [Member] | GBP
Derivatives Fair Value [Line Items]
Derivative, Notional Amount		550,000,000	350,000,000
Notional Amount Of Nonderivative Instruments		1,050,000,000
Not Designated as Hedging Instrument [Member] | CAD
Derivatives Fair Value [Line Items]
Derivative, Notional Amount	[1]	$ 700,000,000	$ 12,000,000

[1] (1) These non-designated instruments represent off-setting forward exchange contracts to manage against adverse movements in exchange rates with regards to the purchase price on pending foreign acquisitions.