Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets
Net operating loss carryforward - U.S. Federal and State	$ 52,499	$ 53,648
Stock-based compensation	7,563	4,245
Allowance for doubtful accounts	170	476
Fair value of derivative instruments	3,222	0
Other	2,471	1,755
Deferred income tax assets	65,925	60,124
Valuation allowance	(1,084)	(1,188)
Net deferred income tax assets	64,841	58,936
Deferred income tax liabilities
Unamortized discount on 4.375% Convertible Senior Notes	0	(382)
Oil and gas properties	(74,247)	(34,985)
Fair value of derivative instruments	(3,249)	(10,222)
Deferred income tax liabilities	(77,496)	(45,589)
Net deferred income tax asset (liability)	$ (12,655)	$ 13,347