Stockholders' Equity - Reclassification out of Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income Tax Expense (Benefit)	$ (1,697)	$ (3,636)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	(23)
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	21	27
Income Tax Expense (Benefit)	(8)	(9)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	13	18
Unrecognized Net Actuarial Loss and Service Credit
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	(205)	(290)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	148	225
Income Tax Expense (Benefit)	21	24
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ (36)	$ (41)