Investments (Details 18)	Sep. 30, 2012	Dec. 31, 2011
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	100.00%	100.00%
Percentage of gross unrealized loss and OTTI loss by industry	100.00%	100.00%
U.S. corporate securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	21.00%	24.00%
RMBS [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	36.00%	30.00%
Foreign corporate securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	16.00%	23.00%
Foreign government debt securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	5.00%	6.00%
Percentage of gross unrealized loss and OTTI loss by industry	5.00%	6.00%
ABS [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	7.00%	5.00%
Percentage of gross unrealized loss and OTTI loss by industry	7.00%	5.00%
State and political subdivision securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	3.00%	3.00%
Percentage of gross unrealized loss and OTTI loss by industry	3.00%	3.00%
CMBS [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	4.00%	4.00%
Other sectors [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by sector	8.00%	5.00%
Mortgage-backed [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	40.00%	34.00%
Finance Domestic Corporate Debt Securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	23.00%	27.00%
Utility Domestic Corporate Debt Securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	7.00%	8.00%
Consumer Domestic Corporate Debt Securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	5.00%	6.00%
Communications Domestic Corporate Debt Securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	3.00%	3.00%
Industrial Domestic Corporate Debt Securities [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	2.00%	2.00%
Other industries [Member]
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Percentage of gross unrealized loss and OTTI loss by industry	5.00%	6.00%