Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Net Income	$ 5,119	$ 3,180	$ 32,521	$ 25,995
Employee Benefits, net of tax:
Amortization of prior service cost, net of tax of $(7), $(5), $(20) and $(18), respectively	(10)	(9)	(30)	(26)
Net gain, net of tax of $62, $26, $187 and $80, respectively	93	39	278	118
Commodity Contract Cash Flow Hedges [Abstract]
Unrealized loss on commodity contract cash flow hedges, net of tax of $(51), $(18), $(29) and $(19), respectively	(75)	(27)	(43)	(28)
Total other comprehensive income	8	3	205	64
Comprehensive Income	$ 5,127	$ 3,183	$ 32,726	$ 26,059