CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable, allowance	$ 160	$ 162
Preferred stock-non-redeemable, par value (in dollars per share)	$ 25	$ 25
Preferred stock-non-redeemable, authorized shares (shares)	2,000	2,000
Preferred stock-non-redeemable, issued shares (shares)	7	7
Preferred stock-non-redeemable, outstanding shares (shares)	7	7
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, authorized shares (shares)	1,600,000	1,600,000
Common stock, issued shares (shares)	554,090	568,517
Common stock, outstanding shares (shares)	554,090	568,517
Customer relationships
Finite-lived intangible assets, accumulated amortization	$ 5,414	$ 4,682
Other intangible assets
Finite-lived intangible assets, accumulated amortization	$ 1,767	$ 1,729