Fair Value (Fair Value Of Assets And Liabilities Measured On Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013		Mar. 31, 2013	Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	$ 112,787		$ 89,132
Securities available for sale:	59,199		69,361
Liability	101,890		89,675
Cash and cash equivalents	90,172		82,574		89,197	75,464
Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and cash equivalents	900		700
Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency derivatives	17		1
Interest rate swaps	18,163		33,543
Money Market Funds, Fair Value	23,034		11,180
Funds held in trust account of Spokane Energy	1,600		1,600
Total	127,864		127,991
Foreign currency derivative liabilities at fair value	0		0
Interest rate swaps	6,696
Total	25,255		29,231
Fair Value, Measurements, Recurring [Member] | Energy commodity derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	17,470		3,876
Liability	2,089		12,796
Fair Value, Measurements, Recurring [Member] | Power Option Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability	428		775
Fair Value, Measurements, Recurring [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability	2,418		1,219
Fair Value, Measurements, Recurring [Member] | Power Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	0		0
Liability	13,624		14,441
Fair Value, Measurements, Recurring [Member] | U.S. Government Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	54,327		61,078
Fair Value, Measurements, Recurring [Member] | Municipal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	3,109		3,518
Fair Value, Measurements, Recurring [Member] | Corporate fixed income - financial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:			3,000
Fair Value, Measurements, Recurring [Member] | Corporate fixed income - industrial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	763		765
Fair Value, Measurements, Recurring [Member] | Certificates of deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	1,000		1,000
Fair Value, Measurements, Recurring [Member] | Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	1,906	[1]	1,960	[1]
Fair Value, Measurements, Recurring [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	6,475	[1]	6,470	[1]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money Market Funds, Fair Value	23,034		11,180
Funds held in trust account of Spokane Energy	1,600		1,600
Total	33,015		21,210
Total	0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed Income Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	1,906	[1]	1,960	[1]
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Deferred compensation assets:	6,475	[1]	6,470	[1]
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency derivatives	47		7
Interest rate swaps	21,260		33,543
Total	171,596		158,154
Foreign currency derivative liabilities at fair value	30		6
Interest rate swaps	12,003
Total	85,030		72,901
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Energy commodity derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	91,090		55,243
Liability	72,997		72,895
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | U.S. Government Agency [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	54,327		61,078
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Municipal [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	3,109		3,518
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate fixed income - financial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:			3,000
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Corporate fixed income - industrial [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	763		765
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Certificates of deposits [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Securities available for sale:	1,000		1,000
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total	390		339
Total	16,860		16,774
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Power Option Agreement [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability	428		775
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability	2,418		1,219
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Power Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	390		339
Liability	14,014		14,780
Fair Value, Measurements, Recurring [Member] | Netting [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Foreign currency derivatives	(30)	[2]	(6)	[2]
Interest rate swaps	(3,097)
Total	(77,137)	[2]	(51,712)	[2]
Foreign currency derivative liabilities at fair value	(30)		(6)
Interest rate swaps	(5,307)
Total	(76,635)	[2]	(60,444)	[2]
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Energy commodity derivatives [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	(73,620)	[2]	(51,367)	[2]
Liability	(70,908)	[2]	(60,099)	[2]
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Natural Gas Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability			0	[2]
Fair Value, Measurements, Recurring [Member] | Netting [Member] | Power Exchange Agreements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gross Asset	(390)		(339)	[2]
Liability	$ (390)		$ (339)	[2]

[1] These assets are trading securities and are included in other property and investments-net on the Condensed Consolidated Balance Sheets.

[2] The Company is permitted to net derivative assets and derivative liabilities with the same counterparty when a legally enforceable master netting agreement exists. In addition, the Company nets derivative assets and derivative liabilities against any payables and receivables for cash collateral held or placed with these same counterparties.