Regulatory assets and liabilities (Tables)

12 Months Ended

Dec. 31, 2014

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	*	2014			2013
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	182,565		$	105,123
Taxes recoverable from customers (a)	Over plant lives		22,910			18,266
Manufactured gas plant sites remediation (a)	Up to 3 years		17,548			15,797
Natural gas costs recoverable through rate adjustments (b)	Up to 28 months		19,575			12,060
Long-term debt refinancing costs (a)	Up to 23 years		7,864			8,697
Costs related to identifying generation development (a)	Up to 12 years		4,165			4,512
Other (a) (b)	Largely within 1- 4 years		14,959			15,311
Total regulatory assets			269,586			179,766
Regulatory liabilities:
Plant removal and decommissioning costs (c)			338,641			308,431
Taxes refundable to customers (c)			17,772			20,180
Natural gas costs refundable through rate adjustments (d)			13,238			16,932
Other (c) (d)			16,601			21,868
Total regulatory liabilities			386,252			367,411
Net regulatory position			$	(116,666	)	$	(187,645	)

* 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 other liabilities 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	*	2014			2013
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	182,565		$	105,123
Taxes recoverable from customers (a)	Over plant lives		22,910			18,266
Manufactured gas plant sites remediation (a)	Up to 3 years		17,548			15,797
Natural gas costs recoverable through rate adjustments (b)	Up to 28 months		19,575			12,060
Long-term debt refinancing costs (a)	Up to 23 years		7,864			8,697
Costs related to identifying generation development (a)	Up to 12 years		4,165			4,512
Other (a) (b)	Largely within 1- 4 years		14,959			15,311
Total regulatory assets			269,586			179,766
Regulatory liabilities:
Plant removal and decommissioning costs (c)			338,641			308,431
Taxes refundable to customers (c)			17,772			20,180
Natural gas costs refundable through rate adjustments (d)			13,238			16,932
Other (c) (d)			16,601			21,868
Total regulatory liabilities			386,252			367,411
Net regulatory position			$	(116,666	)	$	(187,645	)

* 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 other liabilities 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.