Stockholder's Equity (Reclassifications out of AOCI) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax charge on comprehensive income	$ (94)	$ (1,571)	$ (188)	$ (792)
Retirement plans | Reclassifications out of other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of loss and settlement loss	247	1,585	494	2,529
Income tax charge on comprehensive income	(94)	(602)	(188)	(961)
Total	$ 153	$ 983	$ 306	$ 1,568