Stockholder's Equity (Details 2) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income tax credit (provision) on other comprehensive income	$ 3,357	$ (17)	$ 2,565	$ 83
Retirement plans | Reclassifications out of accumulated other comprehensive income (loss)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amortization of (gain) loss	4,292	43	6,820	(202)
Income tax credit (provision) on other comprehensive income	(1,631)	(17)	(2,592)	83
Net of tax	$ 2,661	$ 26	$ 4,228	$ (119)