| Intangible Assets | 
Intangible Assets 
The following table summarizes acquired intangible assets as follows: 
 
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   | 
   | 
March 31, 2018  | 
   | 
December 31, 2017  | 
 
(In thousands)  | 
 Weighted 
Average Life 
 | 
   | 
 Gross Carrying 
Amount 
 | 
   | 
 Accumulated 
Amortization 
 | 
   | 
 Gross Carrying 
Amount 
 | 
   | 
 Accumulated 
Amortization 
 | 
 
Patents  | 
11 Years  | 
   | 
$  | 
2,146  | 
 
  | 
   | 
$  | 
1,651  | 
 
  | 
   | 
$  | 
2,146  | 
 
  | 
   | 
$  | 
1,629  | 
 
  | 
 
Non-compete Agreement  | 
4 Years  | 
   | 
10,900  | 
 
  | 
   | 
2,435  | 
 
  | 
   | 
10,900  | 
 
  | 
   | 
1,687  | 
 
  | 
 
Trade Names  | 
10 Years  | 
   | 
11,516  | 
 
  | 
   | 
4,381  | 
 
  | 
   | 
11,492  | 
 
  | 
   | 
4,114  | 
 
  | 
 
Completed and Unpatented Technology  | 
10 Years  | 
   | 
38,155  | 
 
  | 
   | 
12,938  | 
 
  | 
   | 
38,114  | 
 
  | 
   | 
11,931  | 
 
  | 
 
Backlog  | 
2 Years  | 
   | 
14,424  | 
 
  | 
   | 
13,864  | 
 
  | 
   | 
14,424  | 
 
  | 
   | 
12,184  | 
 
  | 
 
Customer Relationships  | 
15 Years  | 
   | 
138,043  | 
 
  | 
   | 
32,323  | 
 
  | 
   | 
137,967  | 
 
  | 
   | 
30,005  | 
 
  | 
 
Total Intangible Assets  | 
12 Years  | 
   | 
$  | 
215,184  | 
 
  | 
   | 
$  | 
67,592  | 
 
  | 
   | 
$  | 
215,043  | 
 
  | 
   | 
$  | 
61,550  | 
 
  | 
 
  
 
 
All acquired intangible assets other than goodwill and one trade name are being amortized. Amortization expense for acquired intangibles is summarized as follows: 
 
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   | 
   | 
Three Months Ended  | 
 
(In thousands)  | 
   | 
March 31,  2018  | 
   | 
April 1,  2017  | 
 
Amortization Expense  | 
   | 
$  | 
6,001  | 
 
  | 
   | 
$  | 
2,618  | 
 
  | 
 
  
 
 
Amortization expense for acquired intangible assets expected for 2018 and for each of the next five years is summarized as follows:
 
 
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 | 
 | 
 | 
 | 
 
(In thousands)  | 
   | 
 
2018  | 
$  | 
19,372  | 
 
  | 
 
2019  | 
16,700  | 
 
  | 
 
2020  | 
15,975  | 
 
  | 
 
2021  | 
14,065  | 
 
  | 
 
2022  | 
13,631  | 
 
  | 
 
2023  | 
12,463  | 
 
  | 
 
  
 
 
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