Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Current Assets:
Allowance for uncollectible accounts	$ 9	$ 11
Allowance for obsolescence	124	127
Property and equipment additions:
Accumulated depreciation and amortization	10,563	9,340
Other Assets:
Accumulated amortization	$ 806	$ 793
Stockholders' Equity:
Common stock, par value per share (in usd per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,500,000,000	1,500,000,000
Common stock, shares issued	807,525,032	845,048,310
Treasury stock, at cost, shares	21,051,411	19,790,077