Property And Equipment (Schedule Of Asset Retirement Obligation) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation, beginning of period	$ 13,275	$ 12,653
Liabilities incurred	3,556	2,195	1,390
Liabilities settled	(2,465)	(2,271)
Accretion expense	717	698	666
Asset retirement obligation as of end of period	15,083	13,275	12,653
Less current portion	795	60
Asset retirement obligation, long-term	$ 14,288	$ 13,215