We determine if an arrangement is a lease at inception. We have operating leases for office space, sites upon which advertising structures are built, tower space, equipment and automobiles expiring at various dates through October 2049. Some leases have options to extend and some have options to terminate. Operating leases are included in operating lease right-of-use assets, current operating lease liabilities, and noncurrent operating lease liabilities in our condensed consolidated balance sheets.

Operating lease assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. Operating lease assets and liabilities are recognized at commencement date based on the present value of lease payments over the lease term. As our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. We use the implicit rate if it is readily determinable. Our lease terms may include options to extend or terminate the lease, which we treat as exercised when it is reasonably certain and there is a significant economic incentive to exercise that option. Our outdoor advertising segment treats evergreen leases as though they will be automatically renewed at the end of each term.

Operating lease expense for operating lease assets is recognized on a straight-line basis over the lease term. Variable lease payments, which represent lease payments that vary due to changes in facts or circumstances occurring after the commencement date other than the passage of time, are expensed in the period in which the obligation for these payments was incurred. Variable lease expense recognized in the nine months ended September 30, 2021, was not material.

We elected not to apply the recognition requirements of ASC 842, “Leases”, to short-term leases, which are deemed to be leases with a lease term of twelve months or less. Instead, we recognized lease payments in the condensed consolidated statements of operations on a straight-line basis over the lease term and variable payments in the period in which the obligation for these payments was incurred. We elected this policy for all classes of underlying assets. Short-term lease expense recognized in the nine months ended September 30, 2021, was not material.

The impact of operating leases to our condensed consolidated financial statements was as follows:

Three Months Ended

September 30,

Three Months Ended

September 30,

Nine Months Ended

September 30,

Nine Months Ended

September 30,

2020

2021

2020

2021

Operating lease cost

1,247

1,265

3,740

3,769

	Nine Months Ended September 30,		Nine Months Ended September 30,
	2020		2021
Operating cash flows from operating leases	$	3,754	$	3,860
Right-of-use assets obtained in exchange for new operating lease liabilities		—		314

	As of December 31,			As of September 30,
	2020			2021
Weighted average remaining lease term - operating leases (in years)		9.0			9.5
Weighted average discount rate - operating leases		9.1	%		9.3	%

As of September 30, 2021, the annual minimum lease payments of our operating lease liabilities were as follows:

Year ending December 31,
Remainder of 2021	$	1,367
2022		5,368
2023		4,346
2024		2,845
2025		2,829
After 2025		15,358
Total lease payments		32,113
Less imputed interest		10,300
Total recorded lease liabilities	$	21,813

Our outdoor advertising business generates lessor revenue derived from operating leases accounted for under ASC 842, “Leases.” Minimum fixed lease consideration under non-cancelable operating leases for each of the next five years and thereafter, excluding variable lease consideration, as of September 30, 2021, is as follows:

Year ending December 31,
Remainder of 2021	$	2,662
2022		3,180
2023		73
2024		8
2025		—
After 2025		—