Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statement Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Oil and gas revenues	$ 80,715	$ 44,058
Cost and expenses	58,414	34,293
Operating income (loss)	22,301	9,765
Other income and (expense), net	(8,860)	(7,970)
Income (loss) before income taxes	13,441	1,795
Income tax (expense) benefit	(4,018)	(1,060)
Equity in income (loss) of subsidiaries
Net income (loss)	9,423	735
Parent Company [Member]
Oil and gas revenues	6,789	8,775
Cost and expenses	14,547	16,181
Operating income (loss)	(7,758)	(7,406)
Other income and (expense), net	1,127	(4,144)
Income (loss) before income taxes	(6,631)	(11,550)
Income tax (expense) benefit	2,321	3,843
Equity in income (loss) of subsidiaries	14,103	7,621
Net income (loss)	9,793	(86)
Combined Guarantor Subsidiaries [Member]
Oil and gas revenues	73,926	35,283
Cost and expenses	42,678	19,410
Operating income (loss)	31,248	15,873
Other income and (expense), net	(7,546)	(3,826)
Income (loss) before income taxes	23,702	12,047
Income tax (expense) benefit	(8,296)	(4,426)
Net income (loss)	15,406	7,621
Combined Non-Guarantor Subsidiaries [Member]
Cost and expenses	78
Operating income (loss)	(78)
Other income and (expense), net	(2,441)
Income (loss) before income taxes	(2,519)
Income tax (expense) benefit	1,216
Net income (loss)	(1,303)
Eliminations [Member]
Cost and expenses	1,111	(1,298)
Operating income (loss)	(1,111)	1,298
Income (loss) before income taxes	(1,111)	1,298
Income tax (expense) benefit	741	(477)
Equity in income (loss) of subsidiaries	(14,103)	(7,621)
Net income (loss)	$ (14,473)	$ (6,800)