Intangible Assets

3 Months Ended

Mar. 31, 2021

Goodwill And Intangible Assets Disclosure [Abstract]

Intangible Assets

7.   Intangible Assets

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

	(Stated in millions)
	Mar. 31, 2021						Dec. 31, 2020
	Gross		Accumulated		Net Book		Gross		Accumulated		Net Book
	Book Value		Amortization		Value		Book Value		Amortization		Value
Customer relationships	$	1,743	$	507	$	1,236	$	1,744	$	485	$	1,259
Technology/technical know-how		1,284		514		770		1,284		488		796
Tradenames		767		174		593		767		166		601
Other		1,509		711		798		1,488		689		799
	$	5,303	$	1,906	$	3,397	$	5,283	$	1,828	$	3,455

Amortization expense charged to income was $76 million during the first quarter of 2021 and $133 million during the first quarter of 2020.

Based on the net book value of intangible assets at March 31, 2021, amortization charged to income for the subsequent five years is estimated to be: remaining three quarters of 2021—$228 million; 2022—$295 million; 2023—$288 million; 2024—$267 million; 2025—$255 million; and 2026—$252 million.