Derivatives (Narrative) (Details) (USD $) In Millions	1 Months Ended	9 Months Ended
	May 31, 2011	Sep. 30, 2011	Sep. 30, 2010
Number of outstanding interest rate swaps terminated	two
Accumulated OCI gain (loss) net of tax		$ 37.3	$ 12.3
Expected earnings transfer		25.0
Period over which gain included in AOCI will be transferred to earnings, months		12
Interest Rate Swaps [Member] | Cash Flow Hedging [Member]
Increase in interest expenses	1.5
Expense capitalized	1.1