XML 28 R6.htm IDEA: XBRL DOCUMENT

Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
ASSETS
Accumulated depreciation	$ 1,720	$ 1,626

- Definition

The cumulative amount of depreciation, depletion and amortization (related to property, plant and equipment, but not including land) that has been recognized in the income statement.

+ References+ Details