Condensed Consolidating Financial Information (Schedule Of Condensed Consolidating Statement Of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Oil and gas revenues	$ 107,450	$ 96,197	$ 83,818	$ 80,715	$ 55,769	$ 51,668	$ 50,672	$ 44,058	$ 368,180	$ 202,167	$ 138,123
Costs and expenses									269,527	164,016	114,166
OPERATING INCOME	(37,151)	(24,315)	(14,808)	(22,379)	(5,164)	(16,941)	(6,281)	(9,765)	98,653	38,151	23,957
Other income (expense), net									(16,520)	19,994	(5,547)
Income (loss) from continuing operations before income taxes									82,133	58,145	18,410
Income tax (expense) benefit									(30,956)	(25,611)	(6,685)
Equity in income (loss) of subsidiaries									0	0	0
Net income (loss) from continuing operations	16,461	(1,860)	25,900	10,676	4,702	21,491	5,607	735	51,177	32,534	11,725
Net income from discontinued operations, net of income taxes									4,310	4,095	(1,775)
NET INCOME	18,490	(930)	28,504	9,423	6,510	21,643	7,742	735	55,487	36,629	9,950
Parent Company [Member]
Oil and gas revenues									20,195	31,875	33,203
Costs and expenses									76,839	68,652	62,375
OPERATING INCOME									(56,644)	(36,777)	(29,172)
Other income (expense), net									20,022	41,182	4,974
Income (loss) from continuing operations before income taxes									(36,622)	4,405	(24,198)
Income tax (expense) benefit									12,658	(1,209)	8,308
Equity in income (loss) of subsidiaries									73,150	29,319	25,042
Net income (loss) from continuing operations									49,186	32,515	9,152
Net income from discontinued operations, net of income taxes									126	1,013	(1,775)
NET INCOME									49,312	33,528	7,377
Combined Guarantor Subsidiaries [Member]
Oil and gas revenues									347,985	170,292	104,920
Costs and expenses									205,341	100,255	55,815
OPERATING INCOME									142,644	70,037	49,105
Other income (expense), net									(36,542)	(21,188)	(10,521)
Income (loss) from continuing operations before income taxes									106,102	48,849	38,584
Income tax (expense) benefit									(37,136)	(22,612)	(13,542)
Equity in income (loss) of subsidiaries									0	0	0
Net income (loss) from continuing operations									68,966	26,237	25,042
Net income from discontinued operations, net of income taxes									0		0
NET INCOME									68,966	26,237	25,042
Combined Non-Guarantor Subsidiaries [Member]
Oil and gas revenues									0	0	0
Costs and expenses									0	0	0
OPERATING INCOME									0	0	0
Other income (expense), net									0	0	0
Income (loss) from continuing operations before income taxes									0	0	0
Income tax (expense) benefit									0	0	0
Equity in income (loss) of subsidiaries									0	0	0
Net income (loss) from continuing operations									0	0	0
Net income from discontinued operations, net of income taxes									4,184	3,082	0
NET INCOME									4,184	3,082	0
Eliminations [Member]
Oil and gas revenues									0	0	0
Costs and expenses									(12,653)	(4,891)	(4,024)
OPERATING INCOME									12,653	4,891	4,024
Other income (expense), net									0	0	0
Income (loss) from continuing operations before income taxes									12,653	4,891	4,024
Income tax (expense) benefit									(6,478)	(1,790)	(1,451)
Equity in income (loss) of subsidiaries									(73,150)	(29,319)	(25,042)
Net income (loss) from continuing operations									(66,975)	(26,218)	(22,469)
Net income from discontinued operations, net of income taxes									0		0
NET INCOME									$ (66,975)	$ (26,218)	$ (22,469)