Intangible Assets

6 Months Ended

Jun. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Intangible assets consisted of the following:



(In millions)	Gross Carrying Amount		Accumulated Amortization		Net Book Value
June 30, 2019	Gross Carrying Amount		Accumulated Amortization		Net Book Value
Customer related intangible assets	$	2,642	$	1,365	$	1,277
Acquired software and technology	591		505		86
Trade names	120		74		46
Capitalized software development costs	893		353		540
Purchased software	273		120		153
Total	$	4,519	$	2,417	$	2,102



(In millions)	Gross Carrying Amount		Accumulated Amortization		Net Book Value
December 31, 2018	Gross Carrying Amount		Accumulated Amortization		Net Book Value
Customer related intangible assets	$	2,642	$	1,294	$	1,348
Acquired software and technology	591		490		101
Trade names	120		71		49
Capitalized software development costs	810		314		496
Purchased software	261		112		149
Total	$	4,424	$	2,281	$	2,143

The Company estimates that annual amortization expense with respect to acquired intangible assets recorded at June 30, 2019, which include customer related intangible assets, acquired software and technology, and trade names, will be approximately $180 million in 2019, $160 million in 2020, $150 million in each of 2021 and 2022, and $140 million in 2023. Amortization expense with respect to capitalized and purchased software recorded at June 30, 2019 is estimated to approximate $210 million in 2019.