Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net Income	$ 8,029	$ 6,294	$ 28,396	$ 27,403
Other Comprehensive Income (Loss), net of tax:
Amortization of prior service cost, net of tax of $(8), $(7), $(16) and $(14), respectively	(12)	(10)	(24)	(20)
Net gain, net of tax of $67, $62, $133 and $125, respectively	99	93	200	185
Cash Flow Hedges, net of tax:
Unrealized gain on commodity contract cash flow hedges, net of tax of $313, $4, $322 and $21, respectively	496	6	496	32
Total Other Comprehensive Income	583	89	672	197
Comprehensive Income	$ 8,612	$ 6,383	$ 29,068	$ 27,600