Consolidated Statements of Operations and Retained Earnings (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUE AND OTHER INCOME
Oil and natural gas sales	$ 583,109	$ 596,191	$ 373,286
Interest income	2,078	1,216	1,174
Total revenue and other income	585,187	597,407	374,460
EXPENSES
Operating	124,903	86,497	59,446
Depletion, depreciation, accretion and impairment (Note 6)	182,037	231,235	163,573
General and administrative	58,882	60,389	40,241
Other gain (Note 9)	(9,336)	0	0
Equity tax (Note 9)	0	8,271	0
Financial instruments gain (Note 3)	0	(1,522)	(44)
Gain on acquisition (Note 3)	0	(21,699)	0
Foreign exchange loss (gain)	31,338	(11)	16,838
Total expenses	387,824	363,160	280,054
INCOME BEFORE INCOME TAXES	197,363	234,247	94,406
Income tax expense (Note 9)	(97,704)	(107,330)	(57,234)
NET INCOME AND COMPREHENSIVE INCOME	99,659	126,917	37,172
RETAINED EARNINGS, BEGINNING OF YEAR	185,014	58,097	20,925
RETAINED EARNINGS, END OF YEAR	$ 284,673	$ 185,014	$ 58,097
NET INCOME PER SHARE — BASIC	$ 0.35	$ 0.46	$ 0.15
NET INCOME PER SHARE — DILUTED	$ 0.35	$ 0.45	$ 0.14
WEIGHTED AVERAGE SHARES OUTSTANDING - BASIC (Note 7)	280,741,255	273,491,564	253,697,076
WEIGHTED AVERAGE SHARES OUTSTANDING - DILUTED (Note 7)	284,172,254	281,287,002	264,304,831