Leases

12 Months Ended

Dec. 31, 2019

The Company has entered into various operating lease agreements for its offices and co-location assets and related equipment. These operating leases have lease periods expiring between 2020 and 2034. In late 2019, the operating lease for the Company’s corporate headquarters in Cambridge, Massachusetts and an operating sublease for office space both commenced, each with lease terms of 15 years. The Company did not incur a loss associated with this operating sublease arrangement. The Company has not assumed any renewal options in the determination of these lease terms and variable costs are not included as lease components as they are not fixed.

The following table is a summary of the Company’s operating lease costs for the year ended December 31, 2019 (in thousands):



	Real Estate Arrangements			Co-location Arrangements		Total
Operating lease cost	$	63,893		$	96,020	$	159,913
Short-term lease cost	111			14,301		14,412
Variable lease cost	15,610			23,524		39,134
Sublease income	(5,119		)	—		(5,119		)
Total operating lease costs	$	74,495		$	133,845	$	208,340

Lease costs for real estate arrangements are included in general and administrative expenses in the consolidated statements of income. Lease costs for co-location arrangements are primarily included in cost of revenue.

At December 31, 2019, the real estate arrangements' weighted average remaining lease term and weighted average discount rate for operating leases were 12.8 years and 3.5%, respectively. At December 31, 2019, the co-location arrangements' weighted average remaining lease term and weighted average discount rate for operating leases were 3.9 years and 2.2%, respectively.

Maturities of operating lease liabilities as of December 31, 2019 were as follows (in thousands):



	Real Estate Arrangements		Co-location Arrangements
2020	$	77,961	$	63,514
2021	79,303		17,550
2022	75,657		9,603
2023	74,244		6,189
2024	67,727		4,795
Thereafter	532,549		14,695
Total lease payments	907,441		116,346
Less: imputed interest	186,457		5,686
Total lease liabilities	$	720,984	$	110,660

As of December 31, 2019, the Company had additional operating leases, primarily for real estate facilities, that had not yet commenced of $13.7 million, which will commence in 2020 and 2022, with lease terms of one year to seven years. The table above excludes approximately $211.0 million of future sublease income that is expected to be recognized through 2034.

As of December 31, 2019, the Company had outstanding letters of credit in the amount of $7.4 million, primarily related to operating leases. The letters of credit remain in effect until the Company fulfills its obligations under these leases or as such obligations expire under the terms of the letters of credit.

Prior Period Disclosures

The minimum aggregate future obligations under non-cancelable operating leases, including real estate, co-location and bandwidth commitments as of December 31, 2018 were as follows (in thousands):



	Real Estate Arrangements		Bandwidth and Co-location Arrangements
2019	$	54,561	$	138,777
2020	78,683		24,420
2021	75,991		8,463
2022	72,579		5,233
2023	70,101		2,156
Thereafter	599,339		3,709
Total	$	951,254	$	182,758

Rent expense for the years ended December 31, 2018 and 2017 was $63.2 million and $58.8 million, respectively, as determined under the previous standard. The Company has entered into sublease agreements with tenants of various properties previously vacated by the Company. The amounts paid to the Company by these sublease tenants was $3.8 million and $3.6 million for the years ended December 31, 2018 and 2017, respectively.