Investments (Unrealized Losses) (Details)	Dec. 31, 2015 security
Debt securities [Member]
Available-for-Sale Securities and Held-to-Maturity Securities [Line Items]
Gross unrealized losses, number of issues	396
Gross unrealized losses, percentage of total debt	29.70%
Gross unrealized losses, market value as a percent of amortized cost	96.10%
Gross unrealized losses, number of securities with maturities of 12 months or greater	86
Gross unrealized losses, number of securities with maturities of 12 months or greater (as a percentage)	21.70%
Equity Securities [Member]
Available-for-Sale Securities and Held-to-Maturity Securities [Line Items]
Gross unrealized losses, number of securities rated investment grade	21
Other-than-temporarily impaired securities, number of securities rated investment grade	12
External Credit Rating, Investment Grade [Member] | Debt securities [Member]
Available-for-Sale Securities and Held-to-Maturity Securities [Line Items]
Gross unrealized losses, number of securities rated investment grade	387