Related Party Transactions (Details) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2015 USD ($) a joint_venture	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Capital contributed to joint ventures		$ 171,500	$ 0	$ 0
Corporate Joint Venture [Member]
Related Party Transaction [Line Items]
Number of joint ventures | joint_venture	2
Acreage contributed by joint venture partner | a	1,900
Percentage of joint ventures owned by partners		50.00%
Capital commitment to joint ventures	$ 14,000
Capital contributed to joint ventures		$ 4,400