Selected Balance Sheet Data

3 Months Ended

Mar. 31, 2014

Balance Sheet Related Disclosures [Abstract]

Selected Balance Sheet Data

Selected Balance Sheet Data

(Thousands of Dollars)	March 31, 2014			Dec. 31, 2013
Accounts receivable, net (a)
Accounts receivable	$	78,073		$	64,180
Less allowance for bad debts	(5,082		)	(4,911		)
	$	72,991		$	59,269

^(a)  Accounts receivable, net includes $48 and $1,595 due from affiliates as of March 31, 2014 and Dec. 31, 2013, respectively.

(Thousands of Dollars)	March 31, 2014		Dec. 31, 2013
Inventories
Materials and supplies	$	6,563	$	6,437
Fuel	7,119		5,915
Natural gas	813		9,123
	$	14,495	$	21,475

(Thousands of Dollars)	March 31, 2014			Dec. 31, 2013
Property, plant and equipment, net
Electric plant	$	1,943,653		$	1,913,354
Natural gas plant	238,338			236,047
Common and other property	114,712			112,886
Construction work in progress	137,240			127,954
Total property, plant and equipment	2,433,943			2,390,241
Less accumulated depreciation	(958,568		)	(947,462		)
	$	1,475,375		$	1,442,779