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Fair Value Measurements (Schedule Of Change In Asset Retirement Obligation) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Fair Value Measurements [Abstract]
Balance, December 31, 2011	$ 1,845
Additional asset retirement obligation	11
Accretion expense	28	32
Settlements	(75)
Balance, March 31, 2012	$ 1,809

The carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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- Definition

Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability.

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