Supplemental Disclosures (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Summary of current accrued liabilities
Total accrued liabilities	$ 92,369	$ 107,356
Other	2,022	3,489
Accrued evaluated and unproved and unevaluated property costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	54,586	86,259
Accrued support equipment and facilities costs [Member]
Summary of current accrued liabilities
Total accrued liabilities	17,393	4,290
Accrued lease operating expenses [Member]
Summary of current accrued liabilities
Total accrued liabilities	7,743	9,034
Accrued interest on debt [Member]
Summary of current accrued liabilities
Total accrued liabilities	5,806	206
Accrued asset retirement obligations [Member]
Summary of current accrued liabilities
Total accrued liabilities	254	311
Accrued partners' share of joint interest charges [Member]
Summary of current accrued liabilities
Total accrued liabilities	$ 4,565	$ 3,767