Leases (Tables)

6 Months Ended

Jun. 30, 2020

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



	Three Months Ended June 30, 2020						Three Months Ended June 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	17,221	$	4,651	$	21,872	$	14,063	$	4,414	$	18,477
Variable lease cost	40,821		255		41,076		41,529		360		41,889
Short-term lease cost	—		996		996		—		1,812		1,812
Total lease cost	$	58,042	$	5,902	$	63,944	$	55,592	$	6,586	$	62,178



	Six Months Ended June 30, 2020						Six Months Ended June 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total		Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	17,221	$	9,304	$	26,525	$	14,063	$	8,762	$	22,825
Variable lease cost	61,394		498		61,892		58,820		360		59,180
Short-term lease cost	—		1,786		1,786		—		2,665		2,665
Total lease cost	$	78,615	$	11,588	$	90,203	$	72,883	$	11,787	$	84,670

Schedule of future minimum payments

The following tables provide other additional information related to operating lease liabilities:



	June 30, 2020		December 31, 2019
Weighted average remaining lease term	7 years		13 years
Weighted average discount rate (a)	1.66	%	3.71	%

(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.

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



	June 30, 2020
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2020 (remaining six months of 2020)	$	59,555	$	7,817	$	67,372
2021	66,658		13,123		79,781
2022	68,325		9,495		77,820
2023	70,033		7,191		77,224
2024	71,784		4,945		76,729
2025	73,578		3,245		76,823
Thereafter	36,759		36,615		73,374
Total lease commitments	446,692		82,431		529,123
Less imputed interest	16,844		18,807		35,651
Total lease liabilities	$	429,848	$	63,624	$	493,472



	Six Months Ended June 30, 2020		Six Months Ended June 30, 2019
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows (dollars in thousands):	$	7,624	$	11,987