Regulation and Rates (Details) (Subsidiaries [Member], USD $) In Millions, unless otherwise specified	0 Months Ended	1 Months Ended
	Nov. 01, 2012	Jan. 31, 2013	Jun. 30, 2013	May 14, 2012	May 14, 2012 Electric [Member]	Jun. 28, 2012 Natural Gas [Member]	May 14, 2012 Natural Gas [Member]	Jun. 30, 2013 PCA Mechanism [Member] Electric [Member]	Jun. 30, 2013 PCA Mechanism [Member] Gas [Member]	Jun. 30, 2013 Expedited Rate Filing [Member] Electric [Member]	Jun. 30, 2013 Expedited Rate Filing [Member] Gas [Member]	Nov. 01, 2013 Power Cost Only Rate Case (PCORC) [Member] Electric [Member]	Aug. 28, 2013 Power Cost Only Rate Case (PCORC) [Member] Electric [Member]	Apr. 25, 2013 Power Cost Only Rate Case (PCORC) [Member] Electric [Member]	Nov. 01, 2013 Purchased Gas Adjustment (PGA) [Member] Gas [Member]
Regulatory Assets [Line Items]
Rate Case, Approved Effective Weighted Cost of Capital			7.77%	7.80%
Rate Case, Approved Effective Common Equity in Capital Structure			48.00%	48.00%
Rate Case, Approved Effective Return on Equity			9.80%	9.80%
Public Utilities, Rate Case, Requested Rate Increase														$ (0.6)
public utilities rate case requested increase (decrease) percentage														(0.03%)
Public Utilities, Rate Case, Increase (Decrease) in Requested Rate Increase													(1.0)
Public Utilities Rate Case Increase Decrease in Requested Rate Filing Percentage													(0.05%)
Accounting Petition, Approved Effective Increase to Revenue						6.9
Accounting Petition, Approved Effective Increase to Conservation Amortization Expense						6.6
Purchased Gas Adjustment, Annual Decrease in Revenue	77.0
Purchased Gas Adjustment, Annual Decrease in Revenue, Percentage	7.70%
American Recovery and Reinvestment Tax Act of 2009, Grant Amortization Period		10 years
American Recovery and Reinvestment Tax Act of 2009, Grant, Amortization Period Included in Customer Pass Through		11 months
American Recovery and Reinvestment Tax Act of 2009, Grant Pass Through Amount		34.6
American Recovery and Reinvestment Tax Act of 2009, Grant Pass Through Interest Amount		23.8
American Recovery and Reinvestment Tax Act of 2009, Grant, Overall Average Rate Reduction		2.76%
Public Utilities, Rate Case, Approved Effective Annual Rate Increase (Decrease)					$ 63.3		$ 13.4	$ 21.4	$ 10.8	$ 30.7	$ (2.0)	$ (10.5)			$ 4.1
Public Utilities, Rate Case, Approved Effective Annual Rate Percentage Increase (Decrease)					3.20%		1.30%	1.00%	1.10%	1.50%	(0.20%)	(0.50%)			0.40%