Asset retirement obligations

12 Months Ended

Dec. 31, 2018

Asset Retirement Obligation [Abstract]

Asset Retirement Obligations

The Company records obligations related to retirement costs of natural gas distribution mains and lines, natural gas transmission lines, storage facilities, decommissioning of certain electric generating facilities, reclamation of certain aggregate properties, special handling and disposal of hazardous materials at certain electric generating facilities, natural gas distribution facilities and buildings, and certain other obligations as asset retirement obligations.

A reconciliation of the Company's liability, which is included in other accrued liabilities and deferred credits and other liabilities - other on the Consolidated Balance Sheets, for the years ended December 31 was as follows:



	2018			2017
	(In thousands)
Balance at beginning of year	$	341,969		$	314,970
Liabilities incurred	13,424			15,110
Liabilities acquired	1,002			—
Liabilities settled	(3,699		)	(4,981		)
Accretion expense*	18,242			16,839
Revisions in estimates	4,615			31
Balance at end of year	$	375,553		$	341,969


*	Includes $16.8 million and $15.6 million in 2018 and 2017, respectively, related to regulatory assets.

The Company believes that largely all expenses related to asset retirement obligations at the Company's regulated operations will be recovered in rates over time and, accordingly, defers such expenses as regulatory assets. For more information on the Company's regulatory assets and liabilities, see Note 6.