Intangible Assets, Goodwill And Other Assets (Schedule Of Other Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Intangible Assets, Goodwill And Other Assets [Abstract]
CO2 volumetric production payments, net of amortization	$ 12,158	$ 15,852
Other deferred costs and deposits	17,848	16,196
Other assets, net of amortization	$ 30,006	$ 32,048