Derivatives And Hedging Activities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2011 Settled On Maturity [Member]	Dec. 31, 2011 Settled Prior To Maturity [Member]	Jun. 30, 2011 Fair Value Hedges [Member]
Derivative [Line Items]
Notional amount of interest rate fair value hedge derivatives			$ 50	$ 195	$ 245
Aggregate gain on the termination of interest rate swap agreements		13
Notional amount of interest rate cash flow hedge derivatives	98
Cash flow hedge gain (loss) to be reclassified within twelve months	1
Net unrealized gain on foreign currency derivatives designated as cash flow hedges	$ 8.2