Investments (Details 14) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 loan
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	159
Recorded investment of mortgage loans modified as a troubled debt restructuring	$ 13.9
Number of mortgage loans modified as a troubled debt restructuring in payment default	8
Recorded investment of mortgage loans modified as a troubled debt restructuring in payment default	4.7
Commercial mortgage loans
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring with contractual rates altered	1
Brick and mortar
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	1
Recorded investment of mortgage loans modified as a troubled debt restructuring	4.4
Number of mortgage loans modified as a troubled debt restructuring in payment default	1
Recorded investment of mortgage loans modified as a troubled debt restructuring in payment default	4.4
Home equity
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	151
Recorded investment of mortgage loans modified as a troubled debt restructuring	7.9
Number of mortgage loans modified as a troubled debt restructuring in payment default	6
First liens
Mortgage Loan Modifications
Number of mortgage loans modified as a troubled debt restructuring	7
Recorded investment of mortgage loans modified as a troubled debt restructuring	1.6
Number of mortgage loans modified as a troubled debt restructuring in payment default	1
Recorded investment of mortgage loans modified as a troubled debt restructuring in payment default	$ 0.3