Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Abstract]
Proved oil and gas properties	$ 5,156,875	$ 3,713,525
Less: Accumulated depreciation, depletion, amortization and impairment	(1,043,121)	(612,380)
Proved oil and gas properties, net	4,113,754	3,101,145
Unproved oil and gas properties	809,265	815,433
Other property and equipment	313,439	188,468
Less: Accumulated depreciation	(49,672)	(25,296)
Other property and equipment, net	263,767	163,172
Total property, plant and equipment, net	$ 5,186,786	$ 4,079,750