Regulatory assets and liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory assets

The following table summarizes the individual components of unamortized regulatory assets and liabilities as of December 31:

	Estimated Recovery Period	*	2019			2018
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	157,069		$	165,898
Natural gas costs recoverable through rate adjustments (a) (b)	Up to 3 years		89,204			42,652
Asset retirement obligations (a)	Over plant lives		66,000			60,097
Plants to be retired (a)	-		32,931			—
Cost recovery mechanisms (a) (b)	Up to 3 years		19,396			17,948
Manufactured gas plant sites remediation (a)	-		15,347			17,068
Taxes recoverable from customers (a)	Over plant lives		11,486			11,946
Conservation programs (a) (b)	Up to 3 years		7,405			7,494
Long-term debt refinancing costs (a)	Up to 18 years		4,286			4,898
Costs related to identifying generation development (a)	Up to 7 years		2,052			2,508
Other (a) (b)	Up to 19 years		12,221			9,608
Total regulatory assets			$	417,397		$	340,117
Regulatory liabilities:
Taxes refundable to customers (c) (d)			$	249,506		$	277,833
Plant removal and decommissioning costs (c)			173,722			173,143
Natural gas costs refundable through rate adjustments (d)			23,825			29,995
Pension and postretirement benefits (c)			18,065			15,264
Other (c) (d)			25,187			25,197
Total regulatory liabilities			$	490,305		$	521,432
Net regulatory position			$	(72,908	)	$	(181,315	)

* Estimated recovery period for regulatory assets currently being recovered in rates charged to customers.

(a) Included in deferred charges and other assets - other on the Consolidated Balance Sheets.

(b) Included in prepayments and other current assets on the Consolidated Balance Sheets.

(c) Included in deferred credits and other liabilities - other on the Consolidated Balance Sheets.

(d) Included in other accrued liabilities on the Consolidated Balance Sheets.

(e) Recovered as expense is incurred or cash contributions are made.

Regulatory liabilities

The following table summarizes the individual components of unamortized regulatory assets and liabilities as of December 31:

	Estimated Recovery Period	*	2019			2018
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	157,069		$	165,898
Natural gas costs recoverable through rate adjustments (a) (b)	Up to 3 years		89,204			42,652
Asset retirement obligations (a)	Over plant lives		66,000			60,097
Plants to be retired (a)	-		32,931			—
Cost recovery mechanisms (a) (b)	Up to 3 years		19,396			17,948
Manufactured gas plant sites remediation (a)	-		15,347			17,068
Taxes recoverable from customers (a)	Over plant lives		11,486			11,946
Conservation programs (a) (b)	Up to 3 years		7,405			7,494
Long-term debt refinancing costs (a)	Up to 18 years		4,286			4,898
Costs related to identifying generation development (a)	Up to 7 years		2,052			2,508
Other (a) (b)	Up to 19 years		12,221			9,608
Total regulatory assets			$	417,397		$	340,117
Regulatory liabilities:
Taxes refundable to customers (c) (d)			$	249,506		$	277,833
Plant removal and decommissioning costs (c)			173,722			173,143
Natural gas costs refundable through rate adjustments (d)			23,825			29,995
Pension and postretirement benefits (c)			18,065			15,264
Other (c) (d)			25,187			25,197
Total regulatory liabilities			$	490,305		$	521,432
Net regulatory position			$	(72,908	)	$	(181,315	)

* Estimated recovery period for regulatory assets currently being recovered in rates charged to customers.

(a) Included in deferred charges and other assets - other on the Consolidated Balance Sheets.

(b) Included in prepayments and other current assets on the Consolidated Balance Sheets.

(c) Included in deferred credits and other liabilities - other on the Consolidated Balance Sheets.

(d) Included in other accrued liabilities on the Consolidated Balance Sheets.

(e) Recovered as expense is incurred or cash contributions are made.