Income Taxes (Schedule Of Temporary Differences And Resulting Deferred Income Tax Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Income Taxes [Abstract]
Accruals	$ 5,084	$ 3,315
Net operating loss carryforwards	1,314	1,443
Current deferred tax assets, gross	6,398	4,758
Benefit plans	11,237	8,744
Accruals	2,372	1,192
Net operating loss carryforwards	760	1,575
Share-based compensation	7,573	5,742
Partnership interest	1,851	2,002
Investment impairment	1,355
Other	1,316	724
Noncurrent deferred tax assets, gross	26,464	19,979
Less valuation allowance	(1,262)	(163)
Total deferred tax assets	31,600	24,574
Basis differences in intangible assets and property and equipment	(22,860)	(19,346)
Benefit plans	(2,476)	(2,431)
Other	(1,168)	(734)
Total deferred tax liabilities	(26,504)	(22,511)
Net deferred tax assets	$ 5,096	$ 2,063