Derivatives and Hedging Activities Textuals (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Derivatives And Hedging Activities Textuals [Abstract]
Net increase in interest expense on long term debt.	$ 32.0	$ 4.0
Derivative [Line Items]
Notional amount of long-term debt	12,400.0		$ 13,500.0
Loss on net investment hedges	57.0	43.0
Amounts reclassified from AOCI into income	0.0	0.0
Margin on interest rate swap not netted	44.0		55.0
Gain in Changes of Fair Value of Derivatives not designated as hedges	23.0	$ 15.0
Cumulative Fair Value hedging adjustments of hedged item in fair value hedge	116.0		184.0
Notional Amount of Foreign Currency Derivatives	2,900.0		2,900.0
Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of long-term debt	$ 12,500.0		$ 13,800.0