Regulatory assets and liabilities (Tables)

12 Months Ended

Dec. 31, 2018

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	*	2018			2017
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	165,898		$	163,896
Asset retirement obligations (a)	Over plant lives		60,097			56,078
Natural gas costs recoverable through rate adjustments (b)	Up to 1 year		42,652			14,465
Taxes recoverable from customers (a)	Over plant lives		11,946			12,073
Manufactured gas plant sites remediation (a)	-		16,504			18,213
Long-term debt refinancing costs (a)	Up to 19 years		4,898			5,563
Costs related to identifying generation development (a)	Up to 8 years		2,508			2,960
Other (a) (b)	Up to 20 years		35,614			27,715
Total regulatory assets			340,117			300,963
Regulatory liabilities:
Taxes refundable to customers (c)			277,833			279,668
Plant removal and decommissioning costs (c)			173,143			176,190
Natural gas costs refundable through rate adjustments (d)			29,995			28,514
Pension and postretirement benefits (c)			15,264			16,021
Other (c) (d)			25,197			18,905
Total regulatory liabilities			521,432			519,298
Net regulatory position			$	(181,315	)	$	(218,335	)

* 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	*	2018			2017
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	165,898		$	163,896
Asset retirement obligations (a)	Over plant lives		60,097			56,078
Natural gas costs recoverable through rate adjustments (b)	Up to 1 year		42,652			14,465
Taxes recoverable from customers (a)	Over plant lives		11,946			12,073
Manufactured gas plant sites remediation (a)	-		16,504			18,213
Long-term debt refinancing costs (a)	Up to 19 years		4,898			5,563
Costs related to identifying generation development (a)	Up to 8 years		2,508			2,960
Other (a) (b)	Up to 20 years		35,614			27,715
Total regulatory assets			340,117			300,963
Regulatory liabilities:
Taxes refundable to customers (c)			277,833			279,668
Plant removal and decommissioning costs (c)			173,143			176,190
Natural gas costs refundable through rate adjustments (d)			29,995			28,514
Pension and postretirement benefits (c)			15,264			16,021
Other (c) (d)			25,197			18,905
Total regulatory liabilities			521,432			519,298
Net regulatory position			$	(181,315	)	$	(218,335	)

* 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.