Electric Plant and Depreciation (Tables)

9 Months Ended

Sep. 30, 2015

Public Utilities Property Plant And Equipment [Abstract]

Schedule of Major Classes of Electric Plant

The major classes of electric plant are as follows:

(In thousands)	September 30, 2015			December 31, 2014
Electric plant:
Transmission plant	$	1,073,862		$	966,560
Distribution plant		439,098			387,329
General plant		15,617			15,018
Total plant in service		1,528,577			1,368,907
CWIP		85,649			41,222
Total electric plant		1,614,226			1,410,129
Accumulated depreciation		(244,726	)		(220,101	)
Electric plant held for future use		—			37,118
Electric plant, net	$	1,369,500		$	1,227,146