Deferred Policy Acquisition Costs and Present Value of Future Profits (Details Textual) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred policy acquisition costs and present value of future profits	$ 6,336	$ 6,556	$ 9,900
Effect of change [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred policy acquisition costs and present value of future profits		$ (2,188)	$ 2,400