REGULATORY MATTERS: Level 4 (Details) (USD $)	3 Months Ended		12 Months Ended			3 Months Ended	12 Months Ended	3 Months Ended				12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013 Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism	Dec. 31, 2012 Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism	Dec. 27, 2011 Settlement Stipulation - Investment Tax Credits and Idaho Sharing Mechanism	Mar. 31, 2014 Idaho Power Cost Adjustment Mechanism; Update to Base Level Net Power Supply Expense	Dec. 31, 2013 Idaho Power Cost Adjustment Mechanism; Update to Base Level Net Power Supply Expense	Mar. 31, 2014 Annual Idaho Fixed Cost Adjustment Filing	Mar. 14, 2014 Annual Idaho Fixed Cost Adjustment Filing	Jun. 01, 2013 Annual Idaho Fixed Cost Adjustment Filing	Jun. 01, 2012 Annual Idaho Fixed Cost Adjustment Filing	Dec. 31, 2012 IDAHO Idaho and Oregon General Rate Cases and Base Rate Adjustments	Jan. 02, 2012 IDAHO Idaho and Oregon General Rate Cases and Base Rate Adjustments	Dec. 31, 2012 IDAHO Cost Recovery for Langley Gulch Power Plant	Jun. 29, 2012 IDAHO Cost Recovery for Langley Gulch Power Plant	Dec. 31, 2012 OREGON Idaho and Oregon General Rate Cases and Base Rate Adjustments	Mar. 01, 2012 OREGON Idaho and Oregon General Rate Cases and Base Rate Adjustments	Dec. 31, 2012 OREGON Cost Recovery for Langley Gulch Power Plant
Rate Case
Authorized Rate of Return in Rate Case													7.86%				7.757%
Total Retail Rate Base													$ 2,360,000,000
Approved Rate Increase (Decrease), Amount						106,000,000	140,400,000					34,000,000		58,100,000		1,800,000		3,000,000
Public Utilities, Requested Rate Increase (Decrease), Amount						11,100,000		6,000,000
Public Utilities, Approved Return on Equity, Percentage																9.90%
Increase (Decrease) in Rate Base															335,900,000
Authorized Return on Equity in Rate Case, Minimum					9.50%
Authorized Return on Equity in Rate Case, Mid-point					10.00%
Authorized Return on Equity in Rate Case, Maximum					10.50%
Investment Tax Credits, Maximum, in Rate Case					45,000,000
Period of Current ADITC Stipulation					3 years
Percentage to be Shared with Customers					75.00%
Percentage to be Shared with Entity					25.00%
Additional Pension Amortization As Result Of Idaho Settlement Stipulation			16,500,000	14,600,000
Regulatory Liabilities			7,600,000	7,200,000		20,000,000
Increase (Decrease) in Regulatory Assets and Liabilities	(21,479,000)	13,681,000	24,100,000	21,800,000
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount	(950,000)	0
Annual fixed cost adjustment mechanism deferral									$ 14,900,000	$ 8,900,000	$ 10,300,000