| Intangible Assets |
The carrying amounts of intangible assets subject to amortization are included within other long-term assets. The gross carrying amounts of intangible assets, the related accumulated amortization, the net carrying amounts and the weighted-average amortization periods of the Company’s intangible assets are listed in the following tables (in thousands, except amortization period):
| |
|
June 30, 2018 |
|
| |
|
Gross Carrying
Amount |
|
|
Accumulated
Amortization |
|
|
Net Carrying
Amount |
|
|
Weighted-
Average
Amortization
Period (Years) |
|
| Customer relationships |
|
$ |
120,000 |
|
|
$ |
(79,311 |
) |
|
$ |
40,689 |
|
|
|
6.0 |
|
| Licenses |
|
|
3,368 |
|
|
|
(2,213 |
) |
|
|
1,155 |
|
|
|
5.6 |
|
| Total intangible assets
subject to amortization |
|
$ |
123,368 |
|
|
$ |
(81,524 |
) |
|
$ |
41,844 |
|
|
|
|
|
| |
|
December 31, 2017 |
|
| |
|
Gross Carrying
Amount |
|
|
Accumulated
Amortization |
|
|
Net Carrying
Amount |
|
|
Weighted-
Average
Amortization
Period (Years) |
|
| Customer relationships |
|
$ |
120,000 |
|
|
$ |
(66,866 |
) |
|
$ |
53,134 |
|
|
|
6.0 |
|
| Licenses |
|
|
3,368 |
|
|
|
(1,601 |
) |
|
|
1,767 |
|
|
|
5.6 |
|
| Non-compete agreements |
|
|
660 |
|
|
|
(660 |
) |
|
|
— |
|
|
|
1.0 |
|
| Total intangible assets subject to amortization |
|
$ |
124,028 |
|
|
$ |
(69,127 |
) |
|
$ |
54,901 |
|
|
|
|
|
The aggregate amortization expense is as follows (in thousands):
| |
|
Three Months Ended
June 30, |
|
|
Six Months Ended
June 30, |
|
| |
|
2018 |
|
|
2017 |
|
|
2018 |
|
|
2017 |
|
| Amortization expense |
|
$ |
6,553 |
|
|
$ |
7,750 |
|
|
$ |
13,057 |
|
|
$ |
15,665 |
|
The following table sets forth the Company’s estimated aggregate amortization expense for each of the five years below (in thousands):
| Year ended December 31, |
|
Amortization
Expense |
|
| 2019 |
|
$ |
18,489 |
|
| 2020 |
|
|
9,906 |
|
| 2021 |
|
|
75 |
|
| 2022 |
|
|
75 |
|
| 2023 |
|
|
75 |
|
|