Leases (Tables)

9 Months Ended

Sep. 30, 2019

The following tables provide information related to our lease costs for the three and nine months ended September 30, 2019 (dollars in thousands):



	Three Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	21,095	$	4,581	$	25,676
Variable lease cost	36,917		183		37,100
Short-term lease cost	—		812		812
Total lease cost	$	58,012	$	5,576	$	63,588



	Nine Months Ended September 30, 2019
	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
Operating lease cost	$	35,159	$	13,343	$	48,502
Variable lease cost	95,736		543		96,279
Short-term lease cost	—		3,477		3,477
Total lease cost	$	130,895	$	17,363	$	148,258

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



	September 30, 2019
Weighted average remaining lease term	12 years
Weighted average discount rate (a)	3.73	%

(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.



	Nine Months Ended September 30, 2019
Cash paid for amounts included in the measurement of lease liabilities - operating cash flows (dollars in thousands):	$	51,980

Schedule of future minimum payments

The following table provides information related to the maturity of our operating lease liabilities at September 30, 2019 (dollars in thousands):



	September 30, 2019
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019 (remaining three months of 2019)	$	13,625	$	3,352	$	16,977
2020	—		14,083		14,083
2021	—		11,244		11,244
2022	—		7,727		7,727
2023	—		6,101		6,101
2024	—		3,915		3,915
Thereafter	—		38,697		38,697
Total lease commitments	13,625		85,119		98,744
Less imputed interest	19		20,032		20,051
Total lease liabilities	$	13,606	$	65,087	$	78,693

We recognize lease assets and liabilities upon lease commencement. At September 30, 2019, we have additional lease arrangements that have been executed, but have not yet commenced. These arrangements primarily relate to purchased power lease contracts. These leases have commencement dates beginning in June 2020 with terms ending through October 2027. We expect the total fixed consideration paid for these arrangements, which includes both lease and nonlease payments, will approximate $705 million over the term of the arrangements.

The following table provides information related to estimated future minimum operating lease payments at December 31, 2018 (dollars in thousands):



	December 31, 2018
Year	Purchased Power Lease Contracts		Land, Property & Equipment Leases		Total
2019	$	54,499	$	13,747	$	68,246
2020	—		12,428		12,428
2021	—		9,478		9,478
2022	—		6,513		6,513
2023	—		5,359		5,359
Thereafter	—		42,236		42,236
Total future lease commitments	$	54,499	$	89,761	$	144,260