Goodwill (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2013
Changes in goodwill
Balance at beginning of period	$ 2,535
Acquisitions	6
Foreign currency translation adjustments	(17)
Purchase price accounting adjustments and other	(5)
Balance at end of period	2,519
Impairment	0
Transportation
Changes in goodwill
Balance at beginning of period	897
Acquisitions	6
Foreign currency translation adjustments	(10)
Purchase price accounting adjustments and other	(5)
Balance at end of period	888
Facilities
Changes in goodwill
Balance at beginning of period	1,171
Foreign currency translation adjustments	(5)
Balance at end of period	1,166
Supply and Logistics
Changes in goodwill
Balance at beginning of period	467
Foreign currency translation adjustments	(2)
Balance at end of period	$ 465

Carrying amount as of the balance sheet date, which is the cumulative amount paid and (if applicable) the fair value of any noncontrolling interest in the acquiree, adjusted for any amortization recognized prior to the adoption of any changes in generally accepted accounting principles (as applicable) and for any impairment charges, in excess of the fair value of net assets acquired in one or more business combination transactions.

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+ Details

- Definition

The aggregate amount of goodwill acquired in the period and allocated to the reportable segment. The value is stated at fair value based on the purchase price allocation.

+ References+ Details

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

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+ Details