Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net Income	$ 6,294	$ 5,134	$ 27,403	$ 22,815
Employee Benefits, net of tax:
Amortization of prior service cost, net of tax of $(7), $(6), $(14) and $(12), respectively	(10)	(9)	(20)	(18)
Net gain, net of tax of $62, $27, $125 and $53, respectively	93	40	185	79
Commodity Contract Cash Flow Hedges [Abstract]
Unrealized gain (loss) on commodity contract cash flow hedges, net of tax of $4, ($1), $21 and ($1), respectively.	6	(1)	32	(1)
Total other comprehensive income	89	30	197	60
Comprehensive Income	$ 6,383	$ 5,164	$ 27,600	$ 22,875