Discontinued Operations And Other Dispositions (Summary Of Discontinued Operations Presented In Consolidated Statements Of Income And Comprehensive Income) (Details) (USD $) In Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Discontinued Operations And Other Dispositions [Abstract]
Operating revenues	$ 14,224	$ 14,320	$ 31,849	$ 31,755
Total operating expenses	7,269	8,056	22,689	22,924
Operating income	6,955	6,264	9,160	8,831
Estimated loss on disposition	1,254		1,254
Other expense, net	563	517	1,712	1,446
Income from discontinued operations before income taxes	5,138	5,747	6,194	7,385
Provision for income taxes	9,531	2,326	9,931	2,981
(Loss) income from discontinued operations	$ (4,393)	$ 3,421	$ (3,737)	$ 4,404