Asset Retirement Obligations

12 Months Ended

Dec. 31, 2020

Asset Retirement Obligation Disclosure [Abstract]

Asset Retirement Obligations

Asset Retirement ObligationsThe following table reconciles our AROs as of the dates presented, which are included in the “Other liabilities” caption on our Consolidated Balance Sheets: 

	Year Ended December 31,
	2020		2019
Balance at beginning of period	$	4,934	$	4,314
Changes in estimates	33		(2)
Liabilities incurred	121		290
Liabilities settled	—		(67)
Acquisitions of properties	16		83
Accretion expense	357		316
Balance at end of period	$	5,461	$	4,934