Leases (Tables)

6 Months Ended

Jun. 30, 2021

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


	Three Months Ended June 30, 2021						Three Months Ended June 30, 2020
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	29,514	$	4,598	$	34,112	$	17,221	$	4,651	$	21,872
Variable lease cost	40,539		256		40,795		40,821		255		41,076
Short-term lease cost	—		1,260		1,260		—		996		996
Total lease cost	$	70,053	$	6,114	$	76,167	$	58,042	$	5,902	$	63,944


	Six Months Ended June 30, 2021						Six Months Ended June 30, 2020
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	29,514	$	9,239	$	38,753	$	17,221	$	9,304	$	26,525
Variable lease cost	62,027		510		62,537		61,394		498		61,892
Short-term lease cost	—		2,249		2,249		—		1,786		1,786
Total lease cost	$	91,541	$	11,998	$	103,539	$	78,615	$	11,588	$	90,203

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


	Six Months Ended June 30, 2021		Six Months Ended June 30, 2020
Cash paid for amounts included in the measurement of lease liabilities — operating cash flows:	$	13,068	$	7,624
Right-of-use operating lease assets obtained in exchange for operating lease liabilities	248,694		434,997


	June 30, 2021		December 31, 2020
Weighted average remaining lease term	6 years		6 years
Weighted average discount rate (a)	1.72	%	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):


	June 30, 2021
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2021 (remaining six months of 2021)	$	95,596	$	7,762	$	103,358
2022	103,744		11,872		115,616
2023	106,161		9,544		115,705
2024	108,634		6,955		115,589
2025	111,166		5,181		116,347
2026	75,099		3,989		79,088
Thereafter	39,106		34,444		73,550
Total lease commitments	639,506		79,747		719,253
Less imputed interest	25,803		17,613		43,416
Total lease liabilities	$	613,703	$	62,134	$	675,837