Leases (Tables)

9 Months Ended

Sep. 30, 2021

The following tables provide information related to our lease costs (dollars in thousands):


	Three Months Ended September 30, 2021						Three Months Ended September 30, 2020
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	70,102	$	4,626	$	74,728	$	51,662	$	4,655	$	56,317
Variable lease cost	37,586		224		37,810		40,658		232		40,890
Short-term lease cost	—		902		902		—		1,038		1,038
Total lease cost	$	107,688	$	5,752	$	113,440	$	92,320	$	5,925	$	98,245


	Nine Months Ended September 30, 2021						Nine Months Ended September 30, 2020
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	99,616	$	13,865	$	113,481	$	68,883	$	13,959	$	82,842
Variable lease cost	99,613		734		100,347		102,052		730		102,782
Short-term lease cost	—		3,151		3,151		—		2,824		2,824
Total lease cost	$	199,229	$	17,750	$	216,979	$	170,935	$	17,513	$	188,448

The following tables provide other additional information related to operating lease liabilities (dollars in thousands):


	Nine Months Ended September 30, 2021		Nine Months Ended September 30, 2020
Cash paid for amounts included in the measurement of lease liabilities — operating cash flows:	$	85,002	$	56,896
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	251,119		436,587


	September 30, 2021		December 31, 2020
Weighted average remaining lease term	6 years		6 years
Weighted average discount rate (a)	1.75	%	1.69	%

(a) Most of our lease agreements do not contain an implicit rate that is readily determinable. For these agreements we use our incremental borrowing rate to measure the present value of lease liabilities. We determine our incremental borrowing rate at lease commencement based on the rate of interest that we would have to pay to borrow, on a collateralized basis over a similar term, an amount equal to the lease payments in a similar economic environment. We use the implicit rate when it is readily determinable.

Schedule of future minimum payments

The following table provides information related to the maturity of our operating lease liabilities (dollars in thousands):


	September 30, 2021
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2021 (remaining three months of 2021)	$	28,240	$	3,311	$	31,551
2022	103,744		12,323		116,067
2023	106,161		9,995		116,156
2024	108,634		7,373		116,007
2025	111,166		5,564		116,730
2026	75,099		4,343		79,442
Thereafter	39,106		34,912		74,018
Total lease commitments	572,150		77,821		649,971
Less imputed interest	23,721		17,325		41,046
Total lease liabilities	$	548,429	$	60,496	$	608,925