Asset Retirement Obligations - Schedule of Accretion Discount Rates on Interest Method (Details) - USD ($) $ in Thousands				12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Abstract]
Accretion expense on the asset retirement obligation liabilities				$ 623	$ 665	$ 755
Accretion discount rates on interest method	12.09%	11.50%	12.10%	11.50%	10.48%	10.48%