Intangible Assets

12 Months Ended

Dec. 31, 2011

Intangible Assets [Abstract]

Intangible Assets

9.     Intangible Assets

Intangible assets principally comprise technology/technical know-how, tradenames and customer relationships. At December 31, the gross book value and accumulated amortization of intangible assets were as follows:

(Stated in millions)
	2011						2010
	Gross Book Value		Accumulated Amortization		Net Book Value		Gross Book Value		Accumulated Amortization		Net Book Value
Technology/Technical Know-How	$	1,875	$	341	$	1,534	$	1,846	$	215	$	1,631
Tradenames		1,677		131		1,546		1,678		61		1,617
Customer Relationships		1,954		209		1,745		1,963		129		1,834
Other		356		299		57		378		298		80
	$	5,862	$	980	$	4,882	$	5,865	$	703	$	5,162

Amortization expense was $325 million in 2011, $190 million in 2010 and $114 million in 2009.

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

Amortization expense for the subsequent five years is estimated to be as follows: 2012—$323 million, 2013—$304 million, 2014—$298 million, 2015—$287 million and 2016—$268 million.