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Retirement and Share-based Compensation Plans (Valuation Assumptions of Stock Options Granted to Agents) (Details) (Stock Option Plans, Independent Insurance Agent Stock Option Plans [Member])
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Stock Option Plans, Independent Insurance Agent Stock Option Plans [Member]
     
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Average risk-free interest rate 1.21% 0.51% 0.58%
Dividend yield 0.70% 1.20% 1.20%
Average expected life (years) 3 years 9 months 3 years 9 months 3 years 9 months
Volatility 31.20% 41.10% 67.20%