Fair Value Measurements (Details 1) (Embedded derivatives [Member])	3 Months Ended
	Mar. 31, 2012
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Risk margin for uncertainty in cash flows	0.30%
Minimum [Member]
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Adjustment for insurance subsidiary's credit risk	0.50%
Surrenders	4.00%
Partial surrenders	3.00%
Annuitizations	1.00%
Deaths	1.00%
Budgeted option costs	2.50%
Maximum [Member]
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Adjustment for insurance subsidiary's credit risk	2.10%
Surrenders	25.00%
Partial surrenders	5.00%
Annuitizations	2.00%
Deaths	2.50%
Budgeted option costs	4.00%