92 | 2017 form 10-k finite-lived intangible assets are amortized over their estimated useful lives and tested for impairment if events or changes in circumstances indicate that the asset may be impaired .in 2016 , gross customer relationship intangibles of $ 96 million and related accumulated amortization of $ 27 million as well as gross intellectual property intangibles of $ 111 million and related accumulated amortization of $ 48 million from the resource industries segment were impaired .the fair value of these intangibles was determined to be insignificant based on an income approach using expected cash flows .the fair value determination is categorized as level 3 in the fair value hierarchy due to its use of internal projections and unobservable measurement inputs .the total impairment of $ 132 million was a result of restructuring activities and is included in other operating ( income ) expense in statement 1 .see note 25 for information on restructuring costs .amortization expense related to intangible assets was $ 323 million , $ 326 million and $ 337 million for 2017 , 2016 and 2015 , respectively .as of december 31 , 2017 , amortization expense related to intangible assets is expected to be : ( millions of dollars ) .
[['2018', '2019', '2020', '2021', '2022', 'thereafter'], ['$ 322', '$ 316', '$ 305', '$ 287', '$ 268', '$ 613']]
b .goodwill there were no goodwill impairments during 2017 or 2015 .our annual impairment tests completed in the fourth quarter of 2016 indicated the fair value of each reporting unit was substantially above its respective carrying value , including goodwill , with the exception of our surface mining & technology reporting unit .the surface mining & technology reporting unit , which primarily serves the mining industry , is a part of our resource industries segment .the goodwill assigned to this reporting unit is largely from our acquisition of bucyrus international , inc .in 2011 .its product portfolio includes large mining trucks , electric rope shovels , draglines , hydraulic shovels and related parts .in addition to equipment , surface mining & technology also develops and sells technology products and services to provide customer fleet management , equipment management analytics and autonomous machine capabilities .the annual impairment test completed in the fourth quarter of 2016 indicated that the fair value of surface mining & technology was below its carrying value requiring the second step of the goodwill impairment test process .the fair value of surface mining & technology was determined primarily using an income approach based on a discounted ten year cash flow .we assigned the fair value to surface mining & technology 2019s assets and liabilities using various valuation techniques that required assumptions about royalty rates , dealer attrition , technological obsolescence and discount rates .the resulting implied fair value of goodwill was below the carrying value .accordingly , we recognized a goodwill impairment charge of $ 595 million , which resulted in goodwill of $ 629 million remaining for surface mining & technology as of october 1 , 2016 .the fair value determination is categorized as level 3 in the fair value hierarchy due to its use of internal projections and unobservable measurement inputs .there was a $ 17 million tax benefit associated with this impairment charge. .

Question: what is the expected growth rate in amortization expense in 2019?
Answer: -1.9%