CONSOLIDATED STATEMENTS OF CAPITAL STOCK AND LONG-TERM DEBT - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Common Stock, No Par Value	$ 153,045	$ 150,763
Retained Earnings	65,392	55,931
TOTAL COMMON EQUITY	218,437	206,694
TOTAL PREFERRED STOCK	2,436	2,436
SUBTOTAL LONG-TERM DEBT	142,489	140,279
Add: Premium on Issuance of Long-term Debt	1,495	1,707
Less: Unamortized Debt Expense	(3,287)	(3,339)
Less: Current Portion of Long-term Debt	(6,159)	(5,739)
TOTAL LONG-TERM DEBT	134,538	132,908
Convertible Preferred Stock $7.00 Series
SUBTOTAL LONG-TERM DEBT	1,007	1,007
Convertible Preferred Stock $8.00 Series [Member]
SUBTOTAL LONG-TERM DEBT	349	349
Nonredeemable Preferred Stock $7.00 Series
SUBTOTAL LONG-TERM DEBT	80	80
Nonredeemable Preferred Stock $4.75 Series [Member]
SUBTOTAL LONG-TERM DEBT	1,000	1,000
Amortizing Secured Note, due December 20, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	1,415	1,629
Amortizing Secured Note, due May 19, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	4,795	5,215
Amortizing Secured Note, due August 25, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	3,827	4,107
Amortizing Secured Note, due September 19, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	4,107	4,387
State Revolving Trust Note, due December 31, 2022 [Member]
SUBTOTAL LONG-TERM DEBT	329	376
State Revolving Trust Note, due May 1, 2025 [Member]
SUBTOTAL LONG-TERM DEBT	2,062	2,267
State Revolving Trust Note, due March 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	431	469
State Revolving Trust Note2 [Member]
SUBTOTAL LONG-TERM DEBT	465	501
State Revolving Trust Note, due December 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	603	651
State Revolving Trust Bond 4.00% to 5.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	213	254
State Revolving Trust Bond 0.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	166	203
State Revolving Trust Note, due July 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	276	294
State Revolving Trust Note, due January 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	91	97
State Revolving Trust Note, due August 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	1,015	1,066
Amortizing Secured Note, due April 20, 2029 [Member]
SUBTOTAL LONG-TERM DEBT	4,302	4,651
Amortizing Secured Note 7.05%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	3,271	3,521
Amortizing Secured Note 5.69%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	6,709	7,222
Amortizing Secured Note, due April 20, 2040 [Member]
SUBTOTAL LONG-TERM DEBT	14,076	14,707
State Revolving Trust Note, due July 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	2,191	2,303
State Revolving Trust Note, due February 1, 2036 [Member]
SUBTOTAL LONG-TERM DEBT	1,115
State Revolving Trust Note, due November 30, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	1,154	1,216
Construction Loans [Member]
SUBTOTAL LONG-TERM DEBT	7,470
First Mortgage Bonds - Series X [Member]
SUBTOTAL LONG-TERM DEBT	107	162
First Mortgage Bonds - Series Y [Member]
SUBTOTAL LONG-TERM DEBT	122	185
First Mortgage Bonds - Series Z [Member]
SUBTOTAL LONG-TERM DEBT	336	446
First Mortgage Bonds - Series AA [Member]
SUBTOTAL LONG-TERM DEBT	440	565
First Mortgage Bonds - Series BB [Member]
SUBTOTAL LONG-TERM DEBT	603	723
First Mortgage Bonds - Series CC [Member]
SUBTOTAL LONG-TERM DEBT	779	895
First Mortgage Bonds - Series EE [Member]
SUBTOTAL LONG-TERM DEBT	2,713	3,132
First Mortgage Bonds - Series FF [Member]
SUBTOTAL LONG-TERM DEBT	3,690	3,690
First Mortgage Bonds - Series GG [Member]
SUBTOTAL LONG-TERM DEBT	903	993
First Mortgage Bonds - Series HH [Member]
SUBTOTAL LONG-TERM DEBT	960	1,300
First Mortgage Bonds - Series II [Member]
SUBTOTAL LONG-TERM DEBT	700	789
First Mortgage Bonds - Series JJ [Member]
SUBTOTAL LONG-TERM DEBT	824	1,010
First Mortgage Bonds - Series KK [Member]
SUBTOTAL LONG-TERM DEBT	1,078	1,167
First Mortgage Bonds - Series LL [Member]
SUBTOTAL LONG-TERM DEBT	1,175	1,365
First Mortgage Bonds - Series MM [Member]
SUBTOTAL LONG-TERM DEBT	1,337	1,437
First Mortgage Bonds - Series NN [Member]
SUBTOTAL LONG-TERM DEBT	1,590	1,675
First Mortgage Bonds - Series OO [Member]
SUBTOTAL LONG-TERM DEBT	2,258	2,408
First Mortgage Bonds - Series PP [Member]
SUBTOTAL LONG-TERM DEBT	780	815
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	2,408	2,559
First Mortgage Bonds - Series UU [Member]
SUBTOTAL LONG-TERM DEBT	890	935
First Mortgage Bonds - Series VV [Member]
SUBTOTAL LONG-TERM DEBT	2,433	2,577
First Mortgage Bonds - Series WW [Member]
SUBTOTAL LONG-TERM DEBT	$ 865	$ 900