Debt: (Tables)

12 Months Ended

Dec. 31, 2018

Debt:

Schedule of maturities for long-term debt and capital lease obligations

	(dollars in thousands)
	2019		2020		2021		2022		2023
FFB	$	164,782	$	180,107	$	185,476	$	189,176	$	195,483
FMBs		351,010		1,010		1,010		1,010		1,010
PCBs(1)		—		133,550		93,379		18,676		—
CFC		1,035		391		—		—		—
	$	516,827	$	315,058	$	279,865	$	208,862	$	196,493
Capital Leases		5,462		6,082		6,772		7,541		8,398
Total	$	522,289	$	321,140	$	286,637	$	216,403	$	204,891

(1) In addition to regularly scheduled principal payments included are amounts that would be due if the letters of credit supporting the Series 2009 and Series 2010 bonds were drawn upon and became payable in accordance with their terms, such as would occur if the credit facility the letters of credit were issued under was not renewed or extended at its expiration date. These amounts equal $133.6 million in 2020,  $93.4 million in 2021 and $18.7 million in 2022. We anticipate extending these credit facilities before their expiration. The nominal maturities of the Series 2009 and Series 2010 pollution control bonds range from 2030 through 2038.

Schedule of long-term debt outstanding and the associated unamortized debt issuance costs and debt discounts

	2018				2017
			Unamortized Debt				Unamortized Debt
			Issuance Costs and				Issuance Costs and
	Principal		Debt Discounts		Principal		Debt Discounts
	(dollars in thousands)
FFB	$	4,372,422	$	50,210	$	4,192,450	$	51,593
FMBs		3,556,062		41,509		3,057,072		34,673
PCBs		980,770		11,612		980,770		9,347
CFC		1,426		—		2,411		—
	$	8,910,680	$	103,331	$	8,232,703	$	95,613