Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net Income	$ 6,046	$ 8,029	$ 25,190	$ 28,396
Other Comprehensive (Loss) Income, net of tax:
Amortization of prior service cost, net of tax of $(8), $(8), $(16) and $(16), respectively	(12)	(12)	(23)	(24)
Net gain, net of tax of $69, $67, $145 and $133, respectively	101	99	194	200
Cash Flow Hedges, net of tax:
Unrealized (loss)/gain on commodity contract cash flow hedges, net of tax of $(554), $313, $(362) and $322, respectively	(875)	496	(537)	496
Total Other Comprehensive (Loss) Income	(786)	583	(366)	672
Comprehensive Income	$ 5,260	$ 8,612	$ 24,824	$ 29,068