Summary of Significant Accounting Policies (Changes to ARO) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Summary of Significant Accounting Policies [Abstract]
Balance beginning of year	$ 12,074	$ 5,290
Accretion	$ 498	534	$ 182
Acquistion		$ 6,550
Additions
Other	$ (341)	$ (300)
Balance end of year	$ 12,231	$ 12,074	$ 5,290