Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net Income	$ 5,621	$ 5,538	$ 42,589	$ 38,779
Other Comprehensive Income (Loss), net of tax:
Amortization of prior service cost, net of tax of $(5), $(5), $(15) and $(16), respectively	(14)	(14)	(43)	(42)
Net gain, net of tax of $39, $38, $125 and $118, respectively	114	100	355	317
Cash Flow Hedges, net of tax:
Unrealized gain (loss) on commodity contract cash flow hedges, net of tax of $152, $257, $496 and $(70), respectively	324	644	1,193	(83)
Total Other Comprehensive Income, net of tax	424	730	1,505	192
Comprehensive Income	$ 6,045	$ 6,268	$ 44,094	$ 38,971