Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 6,833	$ 4,416	$ 32,023	$ 32,812
Other Comprehensive (Loss) Income, net of tax:
Amortization of prior service cost, net of tax of $(8), $(8), $(23) and $(23), respectively	(11)	(12)	(35)	(37)
Net gain, net of tax of $69, $66, $212 and $200, respectively	102	100	297	300
Cash Flow Hedges, net of tax:
Unrealized (loss)/gain on commodity contract cash flow hedges, net of tax of $(15), $38, $(376) and $360, respectively	(104)	51	(643)	548
Total Other Comprehensive (Loss) Income	(13)	139	(381)	811
Comprehensive Income	$ 6,820	$ 4,555	$ 31,642	$ 33,623