Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2016



	Regulatory Assets
In thousands	2016		2015
Current:
Unrealized loss on derivatives⁽¹⁾	$	1,315	$	22,092
Gas costs	6,830		8,717
Environmental costs⁽²⁾	9,989		9,270
Decoupling⁽³⁾	13,067		18,775
Other⁽⁴⁾	11,161		10,324
Total current	$	42,362	$	69,178
Non-current:
Unrealized loss on derivatives⁽¹⁾	$	913	$	3,447
Pension balancing⁽⁵⁾	50,863		43,748
Income taxes	38,670		43,049
Pension and other postretirement benefit liabilities	183,035		184,223
Environmental costs⁽²⁾	63,970		76,584
Gas costs	89		1,949
Decoupling⁽³⁾	5,860		6,349
Other⁽⁴⁾	14,130		11,362
Total non-current	$	357,530	$	370,711



	Regulatory Liabilities
In thousands	2016		2015
Current:
Gas costs	$	8,054	$	14,157
Unrealized gain on derivatives⁽¹⁾	16,624		2,659
Other⁽⁴⁾	15,612		13,111
Total current	$	40,290	$	29,927
Non-current:
Gas costs	$	1,021	$	8,869
Unrealized gain on derivatives⁽¹⁾	3,265		27
Accrued asset removal costs⁽⁶⁾	341,107		327,047
Other⁽⁴⁾	3,926		3,344
Total non-current	$	349,319	$	339,287