Gross

Carrying

Amount

Accumulated

Amortization

Impairment

Loss

Net

Carrying

Amount

At December 31, 2018

Intangibles subject to amortization:

Customer relationships

$

2,700

$

1,447

$

—

$

1,253

Intangibles not subject to amortization:

Permits

$

10,300

$

—

$

8,600

$

1,700

Tradename

2,500

—

500

2,000

$

12,800

$

—

$

9,100

$

3,700

At March 31, 2018

Intangibles subject to amortization:

Customer relationships

$

2,700

$

1,312

$

—

$

1,388

Intangibles not subject to amortization:

Permits

$

10,300

$

—

$

8,600

$

1,700

Tradename

2,500

—

500

2,000

$

12,800

$

—

$

9,100

$

3,700