Electric Plant and Depreciation (Tables)

12 Months Ended

Dec. 31, 2015

Public Utilities Property Plant And Equipment [Abstract]

Schedule of Major Classes of Electric Plant

The major classes of electric plant are as follows:

	December 31,
(In thousands)	2015			2014
Electric plant:
Transmission plant	$	1,080,050		$	966,560
Distribution plant		457,988			387,329
General plant		15,655			15,018
Total plant in service		1,553,693			1,368,907
CWIP		121,602			41,222
Total electric plant		1,675,295			1,410,129
Accumulated depreciation		(240,764	)		(220,101	)
Electric plant held for future use		—			37,118
Electric plant, net	$	1,434,531		$	1,227,146