Long-Term Debt (Additional Disclosures) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 1997	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Weighted average interest rate on all long-term debt		5.50%	5.50%
Waste Disposal Revenue Bonds Due 2027 [Member]
Debt Instrument [Line Items]
Senior notes, principal amount issued	$ 10,889
Maturity	December 2027	2027
Effective interest rate		0.07%	0.05%