Details of Selected Consolidated Balance Sheet Captions

The following tables provide additional information regarding the composition of certain of our balance sheet captions.

Accounts receivable

Accounts receivable was comprised of the following at September 30, 2018 and 2017:



	September 30
	2018			2017
	(In thousands)
Billed accounts receivable	$	138,794		$	135,091
Unbilled revenue	81,005			73,143
Other accounts receivable	48,291			24,894
Total accounts receivable	268,090			233,128
Less: allowance for doubtful accounts	(14,795		)	(10,865		)
Net accounts receivable	$	253,295		$	222,263

Other current assets

Other current assets as of September 30, 2018 and 2017 were comprised of the following accounts.



	September 30
	2018		2017
	(In thousands)
Deferred gas costs	$	1,927	$	65,714
Prepaid expenses	33,233		32,163
Materials and supplies	8,106		4,472
Assets from risk management activities	1,369		2,436
Other	1,420		1,536
Total	$	46,055	$	106,321

Property, plant and equipment

Property, plant and equipment was comprised of the following as of September 30, 2018 and 2017:



	September 30
	2018			2017
	(In thousands)
Storage plant	$	414,857		$	369,510
Transmission plant	2,851,423			2,521,671
Distribution plant	8,141,733			7,306,021
General plant	771,355			765,728
Intangible plant	38,280			38,980
	12,217,648			11,001,910
Construction in progress	349,725			299,394
	12,567,373			11,301,304
Less: accumulated depreciation and amortization	(2,196,226		)	(2,042,122		)
Net property, plant and equipment⁽¹⁾	$	10,371,147		$	9,259,182


(1)	Net property, plant and equipment includes plant acquisition adjustments of $(55.5) million and $(64.1) million at September 30, 2018 and 2017.

Goodwill

The following presents our goodwill balance allocated by segment and changes in the balance for the fiscal year ended September 30, 2018:



	Distribution		Pipeline and Storage		Total
	(In thousands)
Balance as of September 30, 2017	$	587,080	$	143,052	$	730,132
Deferred tax adjustments on prior acquisitions⁽¹⁾	262		25		287
Balance as of September 30, 2018	$	587,342	$	143,077	$	730,419


(1)	We annually adjust certain deferred taxes recorded in connection with acquisitions completed in fiscal 2001 and fiscal 2005, which resulted in an increase to goodwill and net deferred tax liabilities of $0.3 million for fiscal 2018.

Deferred charges and other assets

Deferred charges and other assets as of September 30, 2018 and 2017 were comprised of the following accounts.



	September 30
	2018		2017
	(In thousands)
Marketable securities	$	99,385	$	88,409
Regulatory assets	141,778		110,977
Assets from risk management activities	250		803
Pension asset	26,972		—
Tax receivable	10,099		—
Other	15,534		20,447
Total	$	294,018	$	220,636

Accounts payable and accrued liabilities

Accounts payable and accrued liabilities as of September 30, 2018 and 2017 were comprised of the following accounts.

Other current liabilities

Other current liabilities as of September 30, 2018 and 2017 were comprised of the following accounts.



	September 30
	2018		2017
	(In thousands)
Customer credit balances and deposits	$	52,648	$	54,627
Accrued employee costs	52,101		46,653
Deferred gas costs	94,705		15,559
Accrued interest	39,486		39,624
Liabilities from risk management activities	56,734		322
Taxes payable	123,457		116,291
Pension and postretirement obligations	10,475		18,411
Regulatory cost of service reserve	22,508		—
Regulatory cost of removal obligation	55,770		35,910
APT annual adjustment mechanism	19,918		—
Regulatory excess deferred taxes (See Note 12)	5,225		—
Other	14,041		5,251
Total	$	547,068	$	332,648

Deferred credits and other liabilities

Deferred credits and other liabilities as of September 30, 2018 and 2017 were comprised of the following accounts.



	September 30
	2018		2017
	(In thousands)
Customer advances for construction	$	11,010	$	9,309
Other regulatory liabilities	78,599		5,257
Asset retirement obligation	12,887		12,827
Liabilities from risk management activities	103		112,076
APT annual adjustment mechanism	15,310		—
Other	40,119		36,266
Total	$	158,028	$	175,735