Annual report pursuant to Section 13 and 15(d)

Reconciliation of Asset Retirement Obligations which are Included in Other Liabilities (Detail)

v3.19.3.a.u2
Reconciliation of Asset Retirement Obligations which are Included in Other Liabilities (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]    
Balance at beginning of period $ 4,314 $ 3,286
Changes in estimates (2) 354
Liabilities incurred 290 335
Liabilities settled (67) (8)
Acquisitions of properties (83) (385)
Asset Retirement Obligation, Sale of Properties 0 (310)
Accretion expense 316 272
Balance at end of period $ 4,934 $ 4,314