Selected Balance Sheet Data (Tables)

9 Months Ended

Sep. 30, 2014

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net

(Thousands of Dollars)	Sept. 30, 2014			Dec. 31, 2013
Accounts receivable, net
Accounts receivable	$	295,333		$	351,180
Less allowance for bad debts	(22,682		)	(22,505		)
	$	272,651		$	328,675

Inventories

(Thousands of Dollars)	Sept. 30, 2014		Dec. 31, 2013
Inventories
Materials and supplies	$	53,979	$	53,127
Fuel	83,507		86,062
Natural gas	126,930		98,818
	$	264,416	$	238,007

Property, Plant and Equipment, Net

(Thousands of Dollars)	Sept. 30, 2014			Dec. 31, 2013
Property, plant and equipment, net
Electric plant	$	10,737,756		$	10,177,056
Natural gas plant	2,930,430			2,757,605
Common and other property	764,710			762,916
Plant to be retired (a)	77,922			101,279
Construction work in progress	995,930			952,469
Total property, plant and equipment	15,506,748			14,751,325
Less accumulated depreciation	(4,193,388		)	(4,008,928		)
	$	11,313,360		$	10,742,397

^(a)  As a result of the 2010 Colorado Public Utilities Commission (CPUC) approval of PSCo’s Clean Air Clean Jobs Act (CACJA) compliance plan and the December 2013 approval of PSCo’s preferred plans for applicable generating resources, PSCo has received approval for early retirement of Cherokee Unit 3 and Valmont Unit 5 between 2015 and 2017. Amounts are presented net of accumulated depreciation.