Stockholders' Equity - Reclassification out of Accumulated Other Comprehensive Income (Loss) (Details) - 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 Expense (Benefit)	$ 3,746	$ (2,623)	$ 10,851	$ 870
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			27
Unrealized Gains on Investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax			79	52
Income Tax Expense (Benefit)			(30)	(20)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			49	32
Unrecognized Net Actuarial Loss and Prior Service Credit, Net
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax			(569)	(705)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax			414	757
Income Tax Expense (Benefit)			133	(20)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax			$ (22)	$ 32