Accumulated Other Comprehensive Income, Reclassified (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Amortization of postretirement benefit plans [Abstract]
Prior service benefit		$ (14)	$ (29)	$ (27)	$ (58)
Unrecognized loss		115	512	390	1,130
Income tax expense		(164)	$ (367)	(272)	$ (608)
Total reclassifications for the period		58		212
Reclassification out of Accumulated Other Comprehensive Income [Member]
Amortization of postretirement benefit plans [Abstract]
Prior service benefit	[1]	(14)		(27)
Unrecognized loss	[1]	115		390
Total before income tax		101		363
Income tax expense		(43)		(151)
Total reclassifications for the period		$ 58		$ 212

[1] These accumulated other comprehensive income components are included in the computation of net periodic postretirement benefit costs, which are included in selling, general and administrative expenses in our consolidated statements of operations (see Note 11 for additional details).