Regulatory assets and liabilities

12 Months Ended

Dec. 31, 2017

Regulatory Assets and Liabilities Disclosure [Abstract]

Regulatory Assets and Liabilities

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



	Estimated Recovery Period	*	2017			2016
			(In thousands)
Regulatory assets:
Pension and postretirement benefits (a)	(e)		$	163,896		$	176,025
Taxes recoverable from customers (a)	Over plant lives		12,073			28,278
Manufactured gas plant sites remediation (a)	-		18,213			18,259
Asset retirement obligations (a)	Over plant lives		56,078			42,580
Natural gas costs recoverable through rate adjustments (b)	Up to 1 year		14,465			2,242
Long-term debt refinancing costs (a)	Up to 20 years		5,563			6,248
Costs related to identifying generation development (a)	Up to 9 years		2,960			3,407
Other (a) (b)	Up to 20 years		27,715			30,281
Total regulatory assets			300,963			307,320
Regulatory liabilities:
Plant removal and decommissioning costs (c)			176,190			176,972
Taxes refundable to customers (c)			279,668			11,010
Pension and postretirement benefits (c)			11,056			9,099
Natural gas costs refundable through rate adjustments (d)			28,514			25,580
Other (c) (d)			23,870			19,191
Total regulatory liabilities			519,298			241,852
Net regulatory position			$	(218,335	)	$	65,468


*	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.

The regulatory assets are expected to be recovered in rates charged to customers. A portion of the Company's regulatory assets are not earning a return; however, these regulatory assets are expected to be recovered from customers in future rates. As of December 31, 2017 and 2016, approximately $269.1 million and $255.4 million, respectively, of regulatory assets were not earning a rate of return.

In the fourth quarter of 2017, the Company performed a one-time revaluation of the Company's regulated deferred tax assets and liabilities for the reduction of the corporate tax rate from 35 percent to 21 percent effective January 1, 2018, as identified in the TCJA. The revaluation of the Company's regulatory deferred tax assets and liabilities are being deferred as the Company works with the various regulators on a plan for amounts expected to be returned to customers, as discussed in Note 16. In the fourth quarter of 2017, the revaluation of the deferred tax assets and liabilities resulted in a decrease of $15.5 million in taxes recoverable from customers and an increase of $270.0 million in taxes refundable to customers. These regulatory amounts are expected to generally be refunded over the remaining life of the related assets as prescribed in the TCJA. The approved regulatory treatment of the impacts of the TCJA by the various regulators may affect the analyses performed.

If, for any reason, the Company's regulated businesses cease to meet the criteria for application of regulatory accounting for all or part of their operations, the regulatory assets and liabilities relating to those portions ceasing to meet such criteria would be removed from the balance sheet and included in the statement of income or accumulated other comprehensive income (loss) in the period in which the discontinuance of regulatory accounting occurs.