Available-for-sale securities (Details) (USD $) In Millions	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Schedule of Available-for-sale Securities.
Cost Basis	$ 1,293	$ 1,301	$ 1,257
Unrealized pretax net gains (losses)	77	21	(125)
Fair Value	1,370	1,322	1,132
U.S. treasury bonds
Schedule of Available-for-sale Securities.
Cost Basis	12	14	14
Unrealized pretax net gains (losses)			1
Fair Value	12	14	15
Other U.S. and non-U.S. government bonds
Schedule of Available-for-sale Securities.
Cost Basis	76	65	15
Unrealized pretax net gains (losses)	1		(1)
Fair Value	77	65	14
Corporate bonds
Schedule of Available-for-sale Securities.
Cost Basis	481	455	343
Unrealized pretax net gains (losses)	30	20	(22)
Fair Value	511	475	321
Asset-backed securities
Schedule of Available-for-sale Securities.
Cost Basis	136	141	165
Unrealized pretax net gains (losses)		(7)	(27)
Fair Value	136	134	138
U.S. governmental agency mortgage-backed securities
Schedule of Available-for-sale Securities.
Cost Basis	258	295	319
Unrealized pretax net gains (losses)	15	13	5
Fair Value	273	308	324
Residential mortgage-backed securities
Schedule of Available-for-sale Securities.
Cost Basis	43	61	79
Unrealized pretax net gains (losses)	(3)	(10)	(19)
Fair Value	40	51	60
Commercial mortgage-backed securities
Schedule of Available-for-sale Securities.
Cost Basis	164	175	176
Unrealized pretax net gains (losses)	4	(13)	(47)
Fair Value	168	162	129
Large capitalization value
Schedule of Available-for-sale Securities.
Cost Basis	100	76	126
Unrealized pretax net gains (losses)	22	13	(13)
Fair Value	122	89	113
Smaller company growth
Schedule of Available-for-sale Securities.
Cost Basis	23	19	20
Unrealized pretax net gains (losses)	8	5	(2)
Fair Value	$ 31	$ 24	$ 18

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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