Investments (Details Textuals 29) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Percentage of gross unrealized loss	100.00%	100.00%
Twenty Percent Or More [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Gross Unrealized Loss	25	49
Twenty Percent Or More [Member] | Six Months Or Greater [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Gross Unrealized Loss	135
Percentage of gross unrealized loss	20.00%
Twenty Percent Or More [Member] | Six Months Or Greater [Member] | Investment Grade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Gross Unrealized Loss	93
Percentage of gross unrealized loss	69.00%
Twenty Percent Or More [Member] | Six Months Or Greater [Member] | External Credit Rating, Non Investment Grade [Member]
Available-for-sale Securities, Continuous Unrealized Loss Position, Qualitative Disclosure [Abstract]
Gross Unrealized Loss	42
Percentage of gross unrealized loss	31.00%