6. Leases

As the lessee, we currently lease real estate space under noncancelable operating lease agreements for our turn-key data centers at NY1, LA1, LA4, DC1, DC2, DE1, and DE2, and our corporate headquarters located in Denver, Colorado. Our leases have remaining lease terms ranging from 1 year to 11 years, some of the leases include options to extend the leases for up to an additional 20 years. We do not include any of our renewal options in our lease terms for calculating our lease liability as the renewal options allow us to maintain operational flexibility and we are not reasonably certain we will exercise these renewal options at this time. The weighted-average remaining non-cancelable lease term for our operating leases was ten years and five years at December 31, 2018, and December 31, 2017, respectively. The weighted-average discount rate was 4.9% and 4.8% at December 31, 2018, and December 31, 2017, respectively.

During the year ended December 31, 2018, we extended the term of approximately 170,000 NRSF of our existing LA1 space from July 2022 to July 2029 and expanded our LA1 facility by leasing an additional 17,238 square feet, which is being developed into turn-key data center space. As a result of this lease modification, we remeasured the lease liability and adjusted the ROU asset by $109.6 million and $109.1 million, respectively. In addition, we assumed a $5.3 million lease liability and ROU asset associated with the acquisition of U.S. Colo in April 2018.

The components of lease expense were as follows (in thousands):


	Year Ended December 31,
	2018		2017		2016
Lease expense:
Operating lease expense	$	22,927	$	20,345	$	19,499
Variable lease expense		4,769		3,780		3,132
Rent expense	$	27,696	$	24,125	$	22,631

The future minimum lease payments to be paid under noncancelable operating leases in effect at December 31, 2018, are as follows (in thousands):


	Operating
Year Ending December 31,	Leases
2019	$	25,712
2020		26,661
2021		26,392
2022		25,995
2023		24,142
Thereafter		129,606
Total lease payments	$	258,508
Less imputed interest		(55,809)
Total	$	202,699