The carrying amounts of intangible assets subject to amortization are included in other long-term assets in the consolidated balance sheets.
Intangible assets consisted of the following (in thousands, except amortization period):
|
|
September 30, 2018 |
|
|
|
Gross Carrying Amount |
|
|
Accumulated Amortization |
|
|
Net Carrying Amount |
|
|
Weighted- Average Amortization Period
(in years)
|
|
Customer relationships |
|
$ |
120,000 |
|
|
$ |
(85,533 |
) |
|
$ |
34,467 |
|
|
|
6.0 |
|
Licenses |
|
|
3,368 |
|
|
|
(2,544 |
) |
|
|
824 |
|
|
|
5.6 |
|
Total intangible assets subject to amortization |
|
$ |
123,368 |
|
|
$ |
(88,077 |
) |
|
$ |
35,291 |
|
|
|
|
|
|
|
December 31, 2017 |
|
|
|
Gross Carrying Amount |
|
|
Accumulated Amortization |
|
|
Net Carrying Amount |
|
|
Weighted- Average Amortization Period
(in 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 following table sets forth the aggregate amortization of intangible assets for the periods presented (in thousands):
|
|
Three Months Ended September 30, |
|
|
Nine Months Ended September 30, |
|
|
|
2018 |
|
|
2017 |
|
|
2018 |
|
|
2017 |
|
Amortization expense |
|
$ |
6,553 |
|
|
$ |
7,780 |
|
|
$ |
19,610 |
|
|
$ |
23,445 |
|
The following table sets forth the estimated annual aggregate amortization of intangible assets for the periods presented (in thousands):
Year Ended December 31, |
|
Amortization Expense |
|
2019 |
|
$ |
18,489 |
|
2020 |
|
|
9,906 |
|
2021 |
|
|
75 |
|
2022 |
|
|
75 |
|
2023 |
|
|
75 |
|
|