Investments (Details Textuals 29) (20% or more [Member], USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross Unrealized Loss	$ 144	$ 223
Six months or greater [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross Unrealized Loss	1,500
Percentage of gross unrealized loss	100.00%
Six months or greater [Member] | Investment Grade [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross Unrealized Loss	598
Percentage of gross unrealized loss	40.00%
Six months or greater [Member] | Below Investment Grade [Member]
Aging of Gross Unrealized Loss and OTTI Loss for Fixed Maturity and Equity Securities Available-for-Sale
Gross Unrealized Loss	$ 914
Percentage of gross unrealized loss	60.00%