Stockholders' Equity (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Reclassifications included in net income:
Net of tax	$ (3,269)	$ 835
Reclassifications from accumulated other comprehensive income (loss)
Reclassifications included in net income:
Pre-tax	(3,843)	630
Tax (expense) benefit	574	205
Net of tax	(3,269)	835
Realized gain on sale of available for sale investment securities | Investment and other income | Reclassifications from accumulated other comprehensive income (loss)
Reclassifications included in net income:
Pre-tax	(2,345)	1,182
Tax (expense) benefit	870	(434)
Net of tax	(1,475)	748
Change in valuation allowance for unrealized gains (losses) on investment securities
Reclassifications included in net income:
Net of tax	(851)	434
Change in valuation allowance for unrealized gains (losses) on investment securities | Provision for income taxes | Reclassifications from accumulated other comprehensive income (loss)
Reclassifications included in net income:
Tax (expense) benefit	(851)	434
Net of tax	(851)	434
Pension and postretirement benefits
Reclassifications included in net income:
Net of tax	(943)	(347)
Pension and postretirement benefits | Underwriting and distribution expense and Compensation and related costs | Reclassifications from accumulated other comprehensive income (loss)
Reclassifications included in net income:
Pre-tax	(1,498)	(552)
Tax (expense) benefit	555	205
Net of tax	$ (943)	$ (347)