Leases (Tables)

6 Months Ended

Jun. 30, 2021

Leases [Abstract]

Schedule of balance sheet impact of leases

For lease agreements entered into or reassessed after the adoption of the new leases standard, we combine lease and nonlease components.

Classification	June 30, 2021		December 31, 2020
	(dollars in thousands)
Right-of-Use Assets—Finance leases
Right-of-use assets	$	302,732	$	302,732
Less: Accumulated provision for depreciation	(264,970)		(262,774)
Total finance lease assets	$	37,762	$	39,958
Lease liabilities—Finance leases
Obligations under finance leases	$	65,207	$	68,876
Long-term debt and finance leases due within one year	7,146		6,773
Total finance lease liabilities	$	72,353	$	75,649

Classification	June 30, 2021		December 31, 2020
	(dollars in thousands)
Right-of-Use Assets—Operating leases
Electric plant in service	$	2,790	$	3,283
Total operating lease assets	$	2,790	$	3,283
Lease liabilities—Operating leases
Capitalization—Other	$	1,970	$	2,388
Other current liabilities	914		990
Total operating lease liabilities	$	2,884	$	3,378

Schedule of lease cost

		Three months ended				Six months ended
Lease Cost	Classification	June 30, 2021		June 30, 2020		June 30, 2021		June 30, 2020
		(dollars in thousands)
Finance lease cost:
Amortization of leased assets	Depreciation and amortization	$	1,517	$	1,344	$	3,033	$	2,688
Interest on lease liabilities	Interest expense	2,044		2,217		4,088		4,434
Operating lease cost:	Inventory(1) & production expense	269		272		539		795
Total leased cost		$	3,830	$	3,833	$	7,660	$	7,917

(1) The majority of our operating lease costs relate to our railcar leases and such costs are added to the cost of our fossil-fuel inventories and are recognized in fuel expense as the inventories are consumed.

Summary of lease terms and discount rates

	June 30, 2021		December 31, 2020
Lease Term and Discount Rate:
Weighted-average remaining lease term (in years)
Finance leases	7.38		7.86
Operating leases	7.57		7.27
Weighted-average discount rate:
Finance leases	11.05	%	11.05	%
Operating leases	4.68	%	4.63	%

Schedule of cash paid for amounts included in the measurement of lease liabilities

	Six months ended
	June 30, 2021		June 30, 2020
	(dollars in thousands)
Other Information:
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from finance leases	$	4,180	$	4,516
Operating cash flows from operating leases	$	539	$	950
Financing cash flows from finance leases	$	3,295	$	2,959
Right-of-use assets obtained in exchange for new operating lease liabilities	$	—	$	1,227

Schedule of maturities of finance and operating lease liabilities

Maturity analysis of our finance and operating lease liabilities as of June 30, 2021 is as follows:

	(dollars in thousands)
Year Ending December 31,	Finance Leases		Operating Leases		Total
2021	$	7,474	$	580	$	8,054
2022	14,949		929		15,878
2023	14,949		708		15,657
2024	14,949		234		15,183
2025	14,949		72		15,021
Thereafter	40,582		1,011		41,593
Total lease payments	$	107,852	$	3,534	$	111,386
Less: imputed interest	(35,499)		(650)		(36,149)
Present value of lease liabilities	$	72,353	$	2,884	$	75,237

Schedule of lessor's income from leases

Lease income recognized during the three and six months ended June 30, 2021 and 2020 was as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2021		2020		2021		2020
	(dollars in thousands)
Lease income	$	1,606	$	1,542	$	3,203	$	3,090