Financial Instruments (Narrative) (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Derivatives, Fair Value [Line Items]
Amount in accumulated other comprehensive income, reclassified as expense to the statement of income	$ 7,300,000
After-tax loss (gain) reclassified from AOCI into income with respect to interest rate contracts	15,211,000	13,380,000	22,351,000
Interest Rate Swap [Member]
Derivatives, Fair Value [Line Items]
Amount deferred in accumulated other comprehensive loss associated with this interest rate swap, net of tax	7,000,000
Forward Rate Contracts [Member]
Derivatives, Fair Value [Line Items]
After-tax loss (gain) reclassified from AOCI into income with respect to interest rate contracts	10,000,000
Amount deferred in accumulated other comprehensive loss associated with this interest rate swap, net of tax		10,800,000
Terminated Interest Rate Swap Hedge [Member]
Derivatives, Fair Value [Line Items]
After-tax loss (gain) reclassified from AOCI into income with respect to interest rate contracts	(400,000)
Amount deferred in accumulated other comprehensive loss associated with this interest rate swap, net of tax		$ (3,000,000)