Stockholders' Equity (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	$ (50,443)	$ (15,859)
Other comprehensive income before reclassification	(516)	483
Amount reclassified from accumulated other comprehensive income	3,269	(835)
Net current period other comprehensive income (loss)	2,753	(352)
Balance at the end of the period	(47,690)	(16,211)
Unrealized gains on investment securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(727)	3,150
Other comprehensive income before reclassification	(327)	307
Amount reclassified from accumulated other comprehensive income	1,475	(748)
Net current period other comprehensive income (loss)	1,148	(441)
Balance at the end of the period	421	2,709
Change in valuation allowance for unrealized gains (losses) on investment securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(1,471)	810
Other comprehensive income before reclassification	(189)	176
Amount reclassified from accumulated other comprehensive income	851	(434)
Net current period other comprehensive income (loss)	662	(258)
Balance at the end of the period	(809)	552
Pension and postretirement benefits
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance at the beginning of the period	(48,245)	(19,819)
Amount reclassified from accumulated other comprehensive income	943	347
Net current period other comprehensive income (loss)	943	347
Balance at the end of the period	$ (47,302)	$ (19,472)