Derivative Instruments And Hedging Activities (Narrative) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
(Proceeds from) or payments to settlement of interest rate protection agreement	$ (9,910,000)
Outstanding senior notes	400,000,000
Senior notes, maturity year	2013
Notional amount of foreign currency exchange contracts outstanding	2,300,000
Foreign currency exchange contracts, expected year of maturity	2011
Amount of gain (loss) to be reclassified from accumulated OCI into income	1,800,000
Amount of gain (loss) to be reclassified from accumulated OCI into income, net of tax	1,200,000
Ineffective portion of derivative instruments	0
Fair value of foreign currency forward contract	100,000
2003 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	(22,800,000)
2008 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	4,400,000
2010 Interest Rate Protection Agreement [Member]
(Proceeds from) or payments to settlement of interest rate protection agreement	$ (9,900,000)