Asset Retirement Obligation
 12 Months Ended
Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]  
Asset Retirement Obligation

5. Asset Retirement Obligation

A summary of the activity related to the asset retirement obligation is as follows:

 

 

 

For the years ended December 31,

 

 

 

2015

 

 

2014

 

 

2013

 

 

 

(in thousands)

 

Asset retirement obligation, beginning of year

 

$

5,557

 

 

$

6,063

 

 

$

6,963

 

Liabilities incurred during period

 

 

302

 

 

 

305

 

 

 

3,416

 

Liabilities settled during period

 

 

(37

)

 

 

(704

)

 

 

(126

)

Accretion expense

 

 

502

 

 

 

506

 

 

 

468

 

Revision in previous estimates and other

 

 

178

 

 

 

32

 

 

 

60

 

Deletions related to property disposals

 

 

(416

)

 

 

(645

)

 

 

(4,718

)

Asset retirement obligation, end of year

 

$

6,086

 

 

$

5,557

 

 

$

6,063

 

 

As of December 31, 2015, the current portion of the Company's asset retirement obligation was $89,000 and was recorded in current liabilities on the consolidated balance sheet.