(7) Goodwill and Other Intangibles:

The changes in the carrying amount of goodwill, net for the years ended December 31, 2018 and 2017 were as follows:



($ in millions)	Goodwill, net

Balance at January 1, 2017	$	9,674
Goodwill Impairment		(2,748)
CTF Acquisition adjustment		98
Balance at December 31, 2017		7,024
Goodwill impairment		(641)
Balance at December 31, 2018	$	6,383

Accumulated goodwill impairment charges were $3,429 million and $2,788 million as of December 31, 2018 and 2017, respectively.

We are required to perform impairment tests related to our goodwill annually, which we perform as of December 31, or sooner if an indicator of impairment occurs. Due to the continued decline in our stock price we had triggering events in the final three quarters of 2018.

We use a market multiples approach to determine fair value. Marketplace company comparisons and analyst reports within the wireline telecommunications industry have historically supported a range of fair values of multiples between 4.4x and 6.5x annualized EBITDA (defined as operating income, net of acquisition and integration costs, pension/OPEB expense, pension settlement costs, stock-based compensation expense, goodwill impairment, storm-related costs, work stoppage costs, and restructuring costs and other charges, as well as depreciation and amortization). We estimated the enterprise fair value using a multiple of 5.5x EBITDA for each of the first three quarterly evaluations in 2018 and used a multiple of 5.3x EBITDA for our fourth quarter evaluation.

We recorded goodwill impairments totaling $641 million for 2018. The driver for the impairment in the third quarter was a reduction in our profitability and utilized EBITDA estimate, which when applied to our market multiple resulted in a lower enterprise valuation. During the fourth quarter, the impairment was largely driven by a lower enterprise valuation resulting from a reduction in utilized market multiple from 5.5x to 5.3x reflecting the lower outlook for our industry as a whole.

Our second and fourth quarter quantitative assessments in 2017 indicated that the carrying value of the enterprise exceeded its fair value and, therefore, an impairment existed. We elected to early adopt the simplified goodwill testing method under ASU 2017-04, recording goodwill impairments totaling $2,748 million for 2017. The driver for the impairment in the second quarter was a reduction in our profitability and utilized EBITDA estimate, which when applied to our market multiple resulted in a lower enterprise valuation. During the fourth quarter, the impairment was largely driven by a lower enterprise valuation resulting from a reduction in utilized market multiple from 5.8x to 5.5x reflecting the lower outlook for our industry as a whole. The revaluation of our net deferred tax liabilities which resulted from the enactment of Tax Cut and Job Act, caused further goodwill impairment (see Note 13). Our first and third quarter quantitative assessments indicated that the fair value of the enterprise exceeded its carrying value and, therefore, no indication of impairment existed in either period.

The market multiples approach that we use incorporates significant estimates and assumptions related to the forecasted results for the remainder of the year including revenues, expenses, and the achievement of other cost synergies. In developing the market multiple, we also consider observed trends of our industry participants. Declines in our industry outlook could also result in future impairments. Our assessment includes many qualitative factors that require significant judgment. Alternative interpretations of these factors could have resulted in different conclusions regarding the need for, or size of, an impairment. Continued declines in our profitability or cash flows or in the sustained, historically low trading prices of our common stock may result in further impairment.

We also considered whether the carrying values of finite-lived intangible assets and property plant and equipment may not be recoverable or whether the carrying value of certain indefinite-lived intangible assets were impaired, noting no additional impairment was present as of December 31, 2018.

The components of other intangibles at December 31, 2018 and 2017 are as follows:



	2018						2017
	Gross				Net		Gross				Net
	Carrying		Accumulated		Carrying		Carrying		Accumulated		Carrying
($ in millions)	Amount		Amortization		Amount		Amount		Amortization		Amount

Other Intangibles:
Customer base	$	5,188	$	(3,848)	$	1,340	$	5,188	$	(3,294)	$	1,894
Trade name		122		-		122		122		-		122
Royalty agreement		72		(40)		32		72		(25)		47
Total other intangibles	$	5,382	$	(3,888)	$	1,494	$	5,382	$	(3,319)	$	2,063

Amortization expense was as follows:



	For the year ended December 31,
($ in millions)	2018		2017		2016

Amortization expense	$	569	$	699	$	643

Amortization expense primarily represents the amortization of our customer base acquired as a result of the CTF Acquisition, the Connecticut Acquisition and the acquisition of certain Verizon properties in 2010 with each based on a useful life of 8 to 12 years on an accelerated method. The approximate weighted average remaining life of our customer base is 5.29 years and for our royalty agreement is 2.25 years. Amortization expense based on our current estimate of useful lives, is estimated to be approximately $454 million in 2019, $354 million in 2020, $260 million in 2021, $173 million in 2022, and $95 million in 2023.