ACI On Demand
ACI On Premise
Total
Gross Balance, prior to December 31, 2018
$ 183,783
$ 773,340
$ 957,123
Total impairment prior to December 31, 2018
—
(47,432)
(47,432 )
Balance, December 31, 2018
183,783
725,908
909,691
Goodwill from acquisitions (1)
370,834
—
370,834
Balance, December 31, 2019
$554,617
$725,908
$1,280,525
goodwill and other intangibles .
in accordance with asc 350 intangibles – goodwill and other the company assesses goodwill for impairment annually during the fourth quarter of its fiscal year using october 1 balances or when there is evidence that events or changes in circumstances indicate that the carrying amount of the asset may not be recovered .
the company evaluates goodwill at the reporting unit level using the discounted cash flow valuation model and allocates goodwill to these reporting units using a relative fair value approach .
during this assessment management relies on a number of factors including operating results business plans and anticipated future cash flows .
the company has identified its reportable segments aci on premise and aci on demand as the reporting units .
the key assumptions used in the discounted cash flow valuation model include discount rates growth rates cash flow projections and terminal value rates .
discount rates growth rates and cash flow projections are the most sensitive and susceptible to change as they require significant management judgment .
discount rates are determined by using a weighted average cost of capital - “ wacc ” .
the wacc considers market and industry data as well as company-specific risk factors .
operational management considering industry and company-specific historical and projected data develops growth rates and cash flow projections for each flow estimates beyond the last projected period assuming a constant wacc and low long-term growth rates .
if the recoverability test indicates potential impairment the company calculates an implied fair value of goodwill for the reporting unit .
the implied fair value of goodwill is determined in a manner similar to how goodwill is calculated in a business combination .
if the implied fair value of goodwill exceeds the carrying value of goodwill assigned to the reporting unit there is no impairment .
if the carrying value of goodwill assigned to the reporting unit exceeds the implied fair value of the goodwill an impairment charge is recorded to write down the carrying value .
the calculated fair value substantially exceeded the current carrying value for all reporting units for all periods .
changes in the carrying amount of goodwill attributable to each reporting unit during the year ended december 31 2019 were as follows -in thousands : .
-1 goodwill from acquisitions relates to the goodwill recorded for the acquisition of e commerce group products inc .
- " ecg " along with ecg ' s subsidiary speedpay inc .
-collectively referred to as " speedpay " and walletron inc .
- " walletron " as discussed in note 3 acquisition .
the purchase price allocations for speedpay and walletron are preliminary as of december 31 2019 and are subject to future changes during the maximum one-year measurement period .
other intangible assets which include customer relationships and trademarks and trade names are amortized using the straight-line method over periods ranging from three years to 20 years .
the company reviews its other intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable .

Question: How did the company amortize other intangible assets?
Answer: using the straight-line method over periods ranging from three years to 20 years.