Fair Value (Carrying amount and estimated fair value of financial instrument assets and liabilities which are not measured at fair value) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Financial Assets [Abstract]
Notes receivable for the issuance of common stock	$ 21	$ 22
Mortgage loans	339	234
Financial Liabilities [Abstract]
Short term debt	83	83
Long term debt	2,526	2,525
Carrying Amount [Member]
Financial Assets [Abstract]
Notes receivable for the issuance of common stock	21	22
Mortgage loans	339	234
Financial Liabilities [Abstract]
Premium deposits and annuity contracts	105	109
Short term debt	83	83
Long term debt	2,526	2,525
Estimate Fair Value [Member]
Financial Assets [Abstract]
Notes receivable for the issuance of common stock	21	22
Mortgage loans	352	247
Financial Liabilities [Abstract]
Premium deposits and annuity contracts	109	114
Short term debt	83	84
Long term debt	2,835	2,679
Estimate Fair Value [Member] | Level 1 [Member]
Financial Assets [Abstract]
Notes receivable for the issuance of common stock
Mortgage loans
Financial Liabilities [Abstract]
Premium deposits and annuity contracts
Short term debt
Long term debt
Estimate Fair Value [Member] | Level 2 [Member]
Financial Assets [Abstract]
Notes receivable for the issuance of common stock
Mortgage loans
Financial Liabilities [Abstract]
Premium deposits and annuity contracts
Short term debt	83
Long term debt	2,835
Estimate Fair Value [Member] | Level 3 [Member]
Financial Assets [Abstract]
Notes receivable for the issuance of common stock	21
Mortgage loans	352
Financial Liabilities [Abstract]
Premium deposits and annuity contracts	109
Short term debt
Long term debt