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CONSOLIDATED STATEMENTS OF CAPITAL STOCK AND LONG-TERM DEBT - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Common Stock, No Par Value	$ 157,354	$ 155,120
Retained Earnings	91,433	74,055
TOTAL COMMON EQUITY	248,787	229,175
TOTAL PREFERRED STOCK	2,433	2,433
SUBTOTAL LONG-TERM DEBT	162,904	147,852
Add: Premium on Issuance of Long-term Debt	1,259	1,367
Less: Unamortized Debt Expense	(3,969)	(3,309)
Less: Current Portion of Long-term Debt	(7,343)	(6,865)
TOTAL LONG-TERM DEBT	152,851	139,045
Convertible Preferred Stock $7.00 Series
SUBTOTAL LONG-TERM DEBT	1,005	1,005
Convertible Preferred Stock $8.00 Series [Member]
SUBTOTAL LONG-TERM DEBT	349	349
Nonredeemable Preferred Stock $7.00 Series
SUBTOTAL LONG-TERM DEBT	79	79
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	924	1,180
Amortizing Secured Note, due May 19, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	3,955	4,375
Amortizing Secured Note, due August 25, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	3,267	3,547
Amortizing Secured Note, due September 19, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	3,547	3,827
State Revolving Trust Note, due December 31, 2022 [Member]
SUBTOTAL LONG-TERM DEBT	228	279
State Revolving Trust Note, due May 1, 2025 [Member]
SUBTOTAL LONG-TERM DEBT	1,632	1,851
State Revolving Trust Note, due March 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	351	392
State Revolving Trust Note2 [Member]
SUBTOTAL LONG-TERM DEBT	389	427
State Revolving Trust Note, due December 1, 2026 [Member]
SUBTOTAL LONG-TERM DEBT	501	553
State Revolving Trust Bond 4.00% to 5.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	111	162
State Revolving Trust Bond 0.00%, due August 1, 2021 [Member]
SUBTOTAL LONG-TERM DEBT	88	128
State Revolving Trust Note, due July 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	235	256
State Revolving Trust Note, due January 1, 2028 [Member]
SUBTOTAL LONG-TERM DEBT	77	84
State Revolving Trust Note, due August 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	907	962
Amortizing Secured Note, due April 20, 2029 [Member]
SUBTOTAL LONG-TERM DEBT	3,604	3,953
Amortizing Secured Note 7.05%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	2,771	3,021
Amortizing Secured Note 5.69%, due January 20, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	5,684	6,197
4.45%, Amortizing Secured Note, due April 20, 2040 [Member]
SUBTOTAL LONG-TERM DEBT	9,387	9,827
4.47%, Amortizing Secured Note, due April 20, 2040 [Member]
SUBTOTAL LONG-TERM DEBT	3,483	3,646
State Revolving Trust Note, due July 1, 2031 [Member]
SUBTOTAL LONG-TERM DEBT	1,954	2,075
State Revolving Trust Note, due February 1, 2036 [Member]
SUBTOTAL LONG-TERM DEBT	1,064	1,115
State Revolving Trust Note, due November 30, 2030 [Member]
SUBTOTAL LONG-TERM DEBT	1,024	1,090
Construction Loans [Member]
SUBTOTAL LONG-TERM DEBT	16,509	3,874
First Mortgage Bonds - Series X [Member]
SUBTOTAL LONG-TERM DEBT		55
First Mortgage Bonds - Series Y [Member]
SUBTOTAL LONG-TERM DEBT		61
First Mortgage Bonds - Series Z [Member]
SUBTOTAL LONG-TERM DEBT	113	224
First Mortgage Bonds - Series AA [Member]
SUBTOTAL LONG-TERM DEBT	155	300
First Mortgage Bonds - Series BB [Member]
SUBTOTAL LONG-TERM DEBT	362	482
First Mortgage Bonds - Series CC [Member]
SUBTOTAL LONG-TERM DEBT	489	636
First Mortgage Bonds - Series EE [Member]
SUBTOTAL LONG-TERM DEBT	1,876	2,296
First Mortgage Bonds - Series FF [Member]
SUBTOTAL LONG-TERM DEBT	2,980	3,495
First Mortgage Bonds - Series GG [Member]
SUBTOTAL LONG-TERM DEBT	723	813
First Mortgage Bonds - Series HH [Member]
SUBTOTAL LONG-TERM DEBT	795	880
First Mortgage Bonds - Series II [Member]
SUBTOTAL LONG-TERM DEBT	520	610
First Mortgage Bonds - Series JJ [Member]
SUBTOTAL LONG-TERM DEBT	671	750
First Mortgage Bonds - Series KK [Member]
SUBTOTAL LONG-TERM DEBT	898	988
First Mortgage Bonds - Series LL [Member]
SUBTOTAL LONG-TERM DEBT	1,010	1,095
First Mortgage Bonds - Series MM [Member]
SUBTOTAL LONG-TERM DEBT	1,137	1,237
First Mortgage Bonds - Series NN [Member]
SUBTOTAL LONG-TERM DEBT	1,415	1,505
First Mortgage Bonds - Series OO [Member]
SUBTOTAL LONG-TERM DEBT	1,956	2,107
First Mortgage Bonds - Series PP [Member]
SUBTOTAL LONG-TERM DEBT	700	740
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	2,107	2,258
First Mortgage Bonds - Series UU [Member]
SUBTOTAL LONG-TERM DEBT	800	845
First Mortgage Bonds - Series VV [Member]
SUBTOTAL LONG-TERM DEBT	2,147	2,290
First Mortgage Bonds - Series WW [Member]
SUBTOTAL LONG-TERM DEBT	795	830
First Mortgage Bonds - Series XX [Member]
SUBTOTAL LONG-TERM DEBT	11,006	11,259
First Mortgage Bonds - Series YY [Member]
SUBTOTAL LONG-TERM DEBT	3,860	3,860
First Mortgage Bonds - Series 2018A [Member]
SUBTOTAL LONG-TERM DEBT	6,917
First Mortgage Bonds - Series 2018B [Member]
SUBTOTAL LONG-TERM DEBT	$ 2,365

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