Preferred Stock - Mezzanine Equity (Details) - USD ($) $ in Thousands			3 Months Ended
	Jan. 23, 2018	Mar. 15, 2017	Mar. 31, 2018	Mar. 31, 2017	[1]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mezzanine equity at December 31, 2017			$ 41,173
Issuance of Series A Preferred Stock, net of issuance cost	$ 48,900	$ 39,000	48,490	$ 38,607
Mezzanine equity at March 31, 2018			90,758
Preferred Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mezzanine equity at December 31, 2017			41,173
Issuance of Series A Preferred Stock, net of issuance cost			48,490
Accumulated dividends on Series A Preferred Stock			1,095
Mezzanine equity at March 31, 2018			$ 90,758

[1] Financial information has been recast to include results attributable to the acquisition of Perigee Energy, LLC by an affiliate on February 3, 2017. See Notes 2 and 4, "Basis of Presentation and Summary of Significant Accounting Policies" and "Acquisitions," respectively, for further discussion.