Intangible Assets

3 Months Ended

Mar. 31, 2012

Intangible Assets [Abstract]

Intangible Assets

8. Intangible Assets

The gross book value, accumulated amortization and net book value of intangible assets were as follows:

									(Stated in millions )
	Mar. 31, 2012						Dec. 31, 2011
	Gross Book Value		Accumulated Amortization		Net Book Value		Gross Book Value		Accumulated Amortization		Net Book Value
Technology/Technical Know-How	$	1,876	$	374	$	1,502	$	1,875	$	341	$	1,534
Tradenames		1,668		138		1,530		1,677		131		1,546
Customer Relationships		1,961		236		1,725		1,954		209		1,745
Other		354		306		48		356		299		57
	$	5,859	$	1,054	$	4,805	$	5,862	$	980	$	4,882

Amortization expense was $80 million during the first quarter of 2012 and $84 million during the same period of 2011.

The weighted average amortization period for all intangible assets is approximately 21 years.

Based on the net book value of intangible assets at March 31, 2012, amortization charged to income for the subsequent five years is estimated to be: remainder of 2012 - $241 million; 2013 - $304 million; 2014 - $298 million; 2015 - $287 million; 2016 - $268 million; and 2017 - $260 million.