GOODWILL AND OTHER INTANGIBLE ASSETS

Changes in the carrying amount of goodwill for our reportable segments for the nine months ended September 30, 2018 were as follows:



	Retail		Group and Specialty		Healthcare Services		Total
	(in millions)
Balance at January 1, 2018	$	1,059	$	261	$	1,961	$	3,281
Acquisitions	476		—		138		614
Balance at September 30, 2018	$	1,535	$	261	$	2,099	$	3,895

The following table presents details of our other intangible assets included in other long-term assets in the accompanying condensed consolidated balance sheets at September 30, 2018 and December 31, 2017.



		September 30, 2018						December 31, 2017
	Weighted Average Life	Cost		Accumulated Amortization		Net		Cost		Accumulated Amortization		Net
		($ in millions)
Other intangible assets:
Customer contracts/ relationships	8.7 years	$	646	$	419	$	227	$	566	$	401	$	165
Trade names and technology	6.4 years	84		82		2		104		84		20
Provider contracts	11.9 years	68		36		32		68		30		38
Noncompetes and other	7.3 years	29		27		2		32		29		3
Total other intangible assets	8.7 years	$	827	$	564	$	263	$	770	$	544	$	226

Amortization expense for other intangible assets was approximately $19 million for the three months ended September 30, 2018 and $18 million for the three months ended September 30, 2017. For the nine months ended September 30, 2018 and 2017, amortization expense for other intangible assets was approximately $70 million and $54 million, respectively. Amortization expense for the nine months ended September 30, 2018 included $12 million associated with the write-off of a trade name value reflecting the re-branding of certain provider assets. The following table presents our estimate of amortization expense for 2018 and each of the five next succeeding years:



	(in millions)
For the years ending December 31,
2018	$	90
2019	70
2020	67
2021	34
2022	31
2023	18