Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014
Other Comprehensive Income (Loss) (AOCI) by component, net of tax
Beginning balance, January 1	$ (11,299)
Ending balance, September 30	(10,707)
Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss) (AOCI) by component, net of tax
Beginning balance, January 1		$ (10,279)
Other comprehensive income (loss) before reclassifications		0
Amounts reclassified from accumulated other comprehensive income (loss)		2,511
Net current period other comprehensive income (loss)		2,511
Ending balance, September 30		(7,768)
Post retirement medical plan | Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss) (AOCI) by component, net of tax
Beginning balance, January 1	(11,299)	(8,242)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	591	474
Net current period other comprehensive income (loss)	591	474
Ending balance, September 30	$ (10,707)	(7,768)
Decker defined benefit pension | Accumulated Other Comprehensive Income (Loss)
Other Comprehensive Income (Loss) (AOCI) by component, net of tax
Beginning balance, January 1		(2,038)
Other comprehensive income (loss) before reclassifications		0
Amounts reclassified from accumulated other comprehensive income (loss)		2,038
Net current period other comprehensive income (loss)		2,038
Ending balance, September 30		$ 0