Business Combination - Allocation of the Consideration Transferred Based on the Fair Values of Assets and Liabilities Acquired (Details) - USD ($) $ in Thousands		3 Months Ended
	Jan. 13, 2016	Mar. 31, 2016	Mar. 31, 2015
Oil and gas properties
Gain on acquisition		$ (11,712)	$ 0
Petroamerica [Member]
Consideration Transferred:
Cash	$ 70,625
Shares of Common Stock issued net of share issue costs	25,811
Consideration transferred	96,436
Oil and gas properties
Proved	48,595
Unproved	50,054
Net working capital (including cash acquired of $19.7 million, restricted cash of $2.5 million and accounts receivable of $5.0 million)	24,202
Long-term restricted cash	8,167
Other long-term assets	1,570
Long-term deferred tax liability	(10,105)
Long-term portion of asset retirement obligation	(11,556)
Other long-term liabilities	(2,779)
Gain on acquisition	(11,712)
Total consideration transferred	96,436
Cash acquired	19,700
Restricted cash acquired	2,500
Accounts receivable acquired	$ 5,000