Stockholders' Equity - Reclassification out of Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income Tax Expense (Benefit)	$ (3,267)	$ 1,697
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	131
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	27	21
Income Tax Expense (Benefit)	(10)	(8)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	17	13
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	(75)	(205)
Other Comprehensive (Income) Loss, Amortization Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Prior Service Cost (Credit), before Tax	139	148
Income Tax Expense (Benefit)	50	21
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 114	$ (36)