Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income	$ 4,416	$ 5,119	$ 32,812	$ 32,521
Other Comprehensive Income (Loss), net of tax:
Amortization of prior service cost, net of tax of $(8), $(7), $(23) and $(20), respectively	(12)	(10)	(37)	(30)
Net gain, net of tax of $66, $62, $200 and $187, respectively	100	93	300	278
Cash Flow Hedges, net of tax:
Unrealized gain (loss) on commodity contract cash flow hedges, net of tax of $38, $(51), $360 and $(29), respectively	51	(75)	548	(43)
Total Other Comprehensive Income	139	8	811	205
Comprehensive Income	$ 4,555	$ 5,127	$ 33,623	$ 32,726