Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017


⁽¹⁾	Unrealized gains or losses on derivatives are non-cash items and, therefore, do not earn a rate of return or a carrying charge. These amounts are recoverable through utility rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.


⁽²⁾	Refer to footnote (3) per the Deferred Regulatory Asset table in Note 15 for a description of environmental costs.


⁽³⁾	This deferral represents the margin adjustment resulting from differences between actual and expected volumes.


⁽⁴⁾	These balances primarily consist of deferrals and amortizations under approved regulatory mechanisms. The accounts being amortized typically earn a rate of return or carrying charge.


⁽⁵⁾	Refer to footnote (1) of the Net Periodic Benefit Cost table per Note 8 for information regarding the deferral of pension expenses.


⁽⁶⁾	Estimated costs of removal on certain regulated properties are collected through rates. See "Accounting Policies—Plant, Property, and Accrued Asset Removal Costs" below.



	Regulatory Assets
In thousands	2017		2016
Current:
Unrealized loss on derivatives⁽¹⁾	$	18,712	$	1,315
Gas costs	154		6,830
Environmental costs⁽²⁾	6,198		9,989
Decoupling⁽³⁾	11,227		13,067
Income taxes	2,218		4,378
Other⁽⁴⁾	7,272		6,783
Total current	$	45,781	$	42,362
Non-current:
Unrealized loss on derivatives⁽¹⁾	$	4,649	$	913
Pension balancing⁽⁵⁾	60,383		50,863
Income taxes	19,991		38,670
Pension and other postretirement benefit liabilities	179,824		183,035
Environmental costs⁽²⁾	72,128		63,970
Gas costs	84		89
Decoupling⁽³⁾	3,970		5,860
Other⁽⁴⁾	15,579		14,130
Total non-current	$	356,608	$	357,530



	Regulatory Liabilities
In thousands	2017		2016
Current:
Gas costs	$	14,886	$	8,054
Unrealized gain on derivatives⁽¹⁾	1,674		16,624
Decoupling⁽³⁾	322		—
Other⁽⁴⁾	17,131		15,612
Total current	$	34,013	$	40,290
Non-current:
Gas costs	$	4,630	$	1,021
Unrealized gain on derivatives⁽¹⁾	1,306		3,265
Decoupling⁽³⁾	957		—
Income taxes	213,306		—
Accrued asset removal costs⁽⁶⁾	360,929		341,107
Other⁽⁴⁾	4,965		3,926
Total non-current	$	586,093	$	349,319


⁽¹⁾	Unrealized gains or losses on derivatives are non-cash items and, therefore, do not earn a rate of return or a carrying charge. These amounts are recoverable through utility rates as part of the annual Purchased Gas Adjustment (PGA) mechanism when realized at settlement.


⁽²⁾	Refer to footnote (3) per the Deferred Regulatory Asset table in Note 15 for a description of environmental costs.


⁽³⁾	This deferral represents the margin adjustment resulting from differences between actual and expected volumes.


⁽⁴⁾	These balances primarily consist of deferrals and amortizations under approved regulatory mechanisms. The accounts being amortized typically earn a rate of return or carrying charge.


⁽⁵⁾	Refer to footnote (1) of the Net Periodic Benefit Cost table per Note 8 for information regarding the deferral of pension expenses.


⁽⁶⁾	Estimated costs of removal on certain regulated properties are collected through rates. See "Accounting Policies—Plant, Property, and Accrued Asset Removal Costs" below.