Stockholders' Equity (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Reclassifications included in net income:
Net of tax	$ 3,878	$ 11,186
Reclassifications from accumulated other comprehensive income
Reclassifications included in net income:
Pre-tax	3,139	9,235
Tax (expense) benefit	739	1,951
Net of tax	3,878	11,186
Unrealized gains on investment securities
Reclassifications included in net income:
Pre-tax	5,146	14,417
Tax (expense) benefit	(1,905)	(5,297)
Net of tax	3,241	9,120
Change in valuation allowance for unrealized gains (losses) on investment securities
Reclassifications included in net income:
Tax (expense) benefit	1,900	5,307
Net of tax	1,900	5,307
Pension and postretirement benefits
Reclassifications included in net income:
Pre-tax	(2,007)	(5,182)
Tax (expense) benefit	744	1,941
Net of tax	$ (1,263)	$ (3,241)