Enterprise-Wide Information (Schedule Of Revenue Attributed To Geographic Areas) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Enterprise Wide Revenue By Type/Geography [Line Items]
Revenues	$ 422,310		$ 395,379		$ 384,952
United States [Member]
Enterprise Wide Revenue By Type/Geography [Line Items]
Revenues	415,869		390,424		379,055
International [Member]
Enterprise Wide Revenue By Type/Geography [Line Items]
Revenues	$ 6,441	[1]	$ 4,955	[1]	$ 5,897	[1]

[1] The revenues of the individual countries comprising these amounts are not significant.