CONDENSED CONSOLIDATED STATEMENTS OF CAPITAL STOCK AND LONG-TERM DEBT (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Common Stock, No Par Value	$ 149,156	$ 148,668
Retained Earnings	49,117	48,623
TOTAL COMMON EQUITY	198,273	197,291
TOTAL PREFERRED STOCK	2,436	2,436
SUBTOTAL LONG-TERM DEBT	142,036	140,029
Add: Premium on Issuance of Long-term Debt	1,867	1,920
Less: Current Portion of Long-term Debt	(6,092)	(5,910)
TOTAL LONG-TERM DEBT	137,811	136,039
Convertible Preferred Stock $7.00 Series [Member]
TOTAL PREFERRED STOCK	1,007	1,007
Convertible Preferred Stock $8.00 Series [Member]
TOTAL PREFERRED STOCK	349	349
Nonredeemable Preferred Stock $7.00 Series [Member]
TOTAL PREFERRED STOCK	80	80
Nonredeemable Preferred Stock $4.75 Series [Member]
TOTAL PREFERRED STOCK	1,000	1,000
Amortizing Secured Note, due December 20, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	1,778	1,825
Amortizing Secured Note, due May 19, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	5,530	5,635
Amortizing Secured Note, due August 25, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	4,317	4,387
Amortizing Secured Note, due September 19, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	4,597	4,667
State Revolving Trust Note, due December 31, 2022 [Member]
SUBTOTAL LONG-TERM DEBT	421	421
State Revolving Trust Note, due May 1, 2025 [Member]
SUBTOTAL LONG-TERM DEBT	2,464	2,463
State Revolving Trust Note, due March 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	488	506
State Revolving Trust Note, due January 25, 2027 [Member]
SUBTOTAL LONG-TERM DEBT	518	536
State Revolving Trust Note, due December 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	697	697
State Revolving Trust Bond 4.00% to 5.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	299	299
State Revolving Trust Bond 0.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	236	241
State Revolving Trust Note, due July 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	313	313
State Revolving Trust Note, due January 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	104	104
State Revolving Trust Note, due August 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	1,090	1,115
Amortizing Secured Note, due April 20, 2029 [Member]
SUBTOTAL LONG-TERM DEBT	4,912	4,999
Amortizing Secured Note 7.05%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	3,708	3,771
Amortizing Secured Note 5.69%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	7,607	7,735
Amortizing Secured Note, due April 20, 2040 [Member]
SUBTOTAL LONG-TERM DEBT	11,000	8,000
State Revolving Trust Note, due July 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	2,411	2,411
State Revolving Trust Note, due November 30, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	1,276	1,276
First Mortgage Bonds - Series X [Member]
SUBTOTAL LONG-TERM DEBT	211	215
First Mortgage Bonds - Series Y [Member]
SUBTOTAL LONG-TERM DEBT	245	245
First Mortgage Bonds - Series Z [Member]
SUBTOTAL LONG-TERM DEBT	548	559
First Mortgage Bonds - Series AA [Member]
SUBTOTAL LONG-TERM DEBT	700	700
First Mortgage Bonds - Series BB [Member]
SUBTOTAL LONG-TERM DEBT	827	845
First Mortgage Bonds - Series CC [Member]
SUBTOTAL LONG-TERM DEBT	1,025	1,025
First Mortgage Bonds - Series EE [Member]
SUBTOTAL LONG-TERM DEBT	3,468	3,550
First Mortgage Bonds - Series FF [Member]
SUBTOTAL LONG-TERM DEBT	4,900	4,900
First Mortgage Bonds - Series GG [Member]
SUBTOTAL LONG-TERM DEBT	1,064	1,083
First Mortgage Bonds - Series HH [Member]
SUBTOTAL LONG-TERM DEBT	1,390	1,390
First Mortgage Bonds - Series II [Member]
SUBTOTAL LONG-TERM DEBT	861	881
First Mortgage Bonds - Series JJ [Member]
SUBTOTAL LONG-TERM DEBT	1,090	1,090
First Mortgage Bonds - Series KK [Member]
SUBTOTAL LONG-TERM DEBT	1,233	1,255
First Mortgage Bonds - Series LL [Member]
SUBTOTAL LONG-TERM DEBT	1,435	1,435
First Mortgage Bonds - Series MM [Member]
SUBTOTAL LONG-TERM DEBT	1,504	1,537
First Mortgage Bonds - Series NN [Member]
SUBTOTAL LONG-TERM DEBT	1,755	1,755
First Mortgage Bonds - Series OO [Member]
SUBTOTAL LONG-TERM DEBT	2,508	2,559
First Mortgage Bonds - Series PP [Member]
SUBTOTAL LONG-TERM DEBT	850	850
First Mortgage Bonds - Series QQ [Member]
SUBTOTAL LONG-TERM DEBT	9,915	9,915
First Mortgage Bonds - Series RR [Member]
SUBTOTAL LONG-TERM DEBT	22,500	22,500
First Mortgage Bonds - Series SS [Member]
SUBTOTAL LONG-TERM DEBT	23,000	23,000
First Mortgage Bonds - Series TT [Member]
SUBTOTAL LONG-TERM DEBT	2,659	2,709
First Mortgage Bonds - Series UU [Member]
SUBTOTAL LONG-TERM DEBT	975	975
First Mortgage Bonds - Series VV [Member]
SUBTOTAL LONG-TERM DEBT	2,672	2,720
First Mortgage Bonds - Series WW [Member]
SUBTOTAL LONG-TERM DEBT	$ 935	$ 935