right-of-use

asset of $64,497, short-term lease liability of $20,632 and long-term lease liability of $44,759 were reflected on the balance sheet as of December 31, 2019.

The elements of lease expense were as follows:


	Twelve Months Ended December 31, 2019
Lease cost:
Operating lease(1)	$	23,176
Leases with a term less than 12 months		4,305

Total lease cost	$	27,481

(1)	Operating lease cost includes an immaterial amount of variable expenses and sublease rental income.

The weighted average discount rate and the weighted average remaining lease term were 3.8% and 4.9 years, respectively, for the period ended December 31, 2019. Operating cash flows used for operating leases for the twelve months ended December 31, 2019 was $23,356.

In 2019, the Company sold two buildings in Boulder, Colorado, and three buildings in Portland, Oregon, as part of sale and leaseback transactions, and will lease back the buildings over varying terms into 2021. Total net cash proceeds received for these two transactions were $41,179 and the Company recognized a net gain on the sale of these long-lived assets of

$6,773.

Future lease payments under

non-cancelable

leases as of December 31, 2019 are detailed as follows:


Year Ending December 31,	Amount
2020	$	22,299
2021		14,862
2022		9,006
2023		7,563
2024		6,660
Thereafter		11,387

Total lease payments		71,777
Less: imputed interest		6,386

Total operating lease liabilities	$	65,391

Amounts presented above do not include payments relating to immaterial leases excluded from the balance sheet as part of transition elections adopted upon implementation of ASU

2016-02,

as well as operating leases with terms of less than twelve months. Additionally, we have excluded approximately $126,400 of lease payments (undiscounted basis) that have not yet commenced. These leases commence in 2020 with lease terms expected between 20 and 21 years.

Minimum lease payments under operating leases as of December 31, 2018, prior to adoption of ASU

2016-02

were as follows:


Year Ending December 31,	Amount
2019	$	20,106
2020		17,142
2021		10,325
2022		5,573
2023		4,410
Thereafter		8,739

Total minimum lease payments	$	66,295