Summary of Significant Accounting Policies Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Drilling and Related Costs Capitalized	$ 12,900	$ 6,000
Write-downs	4,446	313,337	$ 1,472,721
Restricted Cash and Cash Equivalents	$ 17,600	$ 11,600