Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Public Utilities, Property, Plant and Equipment [Abstract]

Major Classifications Of Property, Plant And Equipment And Accumulated Depreciation [Text Block]

In thousands	2017		2016
Utility plant in service	$	2,975,217	$	2,843,243
Utility construction work in progress	159,924		62,264
Less: Accumulated depreciation	942,879		903,096
Utility plant, net	2,192,262		2,002,411
Non-utility plant in service	65,372		63,765
Non-utility construction work in progress	4,122		3,868
Less: Accumulated depreciation	17,598		16,345
Non-utility plant, net	51,896		51,288
Total property, plant, and equipment	$	2,244,158	$	2,053,699
Capital expenditures in accrued liabilities	$	34,761	$	9,545