The Company leases office facilities under non-cancelable operating leases that expire at various dates through February 2035.

Operating lease expense costs were $47.5 in 2021, $44.6 million in 2020, and $32.2 million in 2019.

The Company subleases some of its unused spaces to third parties. Operating sublease income generated under all operating lease agreements is as follows:


	Year ended December 31,
	2021		2020		2019
	(in thousands)
Operating sublease income	$	4,954	$	5,000	$	2,498

The following table provides a reconciliation between non-cancelable lease commitments and lease liabilities as of December 31, 2021:


	Operating leases
Lease commitments (Note 11)	$	385,997
Less: Legally binding minimum lease payments for leases signed but not yet commenced		—
Less: Present value discount		75,760
Total lease liabilities	$	310,237

During the year ended December 31, 2021, the Company terminated a lease for certain office facilities in Cambridge, Massachusetts and recorded a gain of $4.3 million. In connection with the lease termination, the Company recorded a loss of $6.5 million for the disposal of fixed assets. The net loss of $2.2 million is reported in the consolidated statements of operations as operating expense.

The Company uses its estimated incremental borrowing rate, which is derived from information available at the lease commencement date, in determining the present value of operating lease payments. To determine the estimated incremental borrowing rate, the Company uses publicly available credit ratings for peer companies. The Company estimates the incremental borrowing rate using yields for maturities that are in line with the duration of the lease payments.

The following table provides weighted average remaining lease terms and weighted average discount rate for operating and finance leases as of December 31, 2021:


Weighted-average remaining lease term:		9.6 years
Weighted-average discount rate:		4.5%

Cash payments related to operating lease liabilities were $49.5 million in 2021, $48.8 million in 2020, and $28.8 million in 2019.