Certain of the Company’s investments in real estate are subject to ground leases. The Company’s ground leases are classified as either operating leases or financing leases based on the characteristics of each lease. As of September 30, 2019, the Company had 15 ground leases classified as operating and two ground leases classified as financing. Each of the Company’s ground leases were acquired as part of the acquisition of real estate and no incremental costs were incurred for such ground leases. The Company’s ground leases are non-cancelable, and two of the Company’s operating leases contain renewal options for additional 99 and 10 year terms. The following table presents the future lease payments due under the Company’s ground leases ($ in thousands):

	Operating Leases			Financing Leases
2019 (remaining)	$	990		$	737
2020		3,879			2,991
2021		3,982			3,081
2022		4,093			3,174
2023		4,134			3,269
2024		4,305			3,367
Thereafter		594,510			330,548
Total undiscounted future lease payments		615,893			347,167
Difference between undiscounted cash flows and discounted cash flows		(536,622	)		(290,653	)
Total lease liability	$	79,271		$	56,514

The Company utilized its incremental borrowing rate, which was between 5% and 7%, to determine its lease liabilities. As of September 30, 2019, the weighted average remaining lease term of the Company’s operating leases and financing leases was 57 years and 77 years, respectively.

The following table presents the future lease payments due under the Company’s ground leases as of December 31, 2018, prior to the adoption of ASU 2016-02 ($ in thousands):

Year	Future Commitments
2019	$	1,470
2020		1,508
2021		1,547
2022		1,586
2023		1,622
Thereafter		460,055
Total	$	467,788

Payments under the Company’s ground leases primarily contain fixed payment components that may include periodic increases fixed to an index or periodic fixed percentage escalations. One of the Company’s ground leases contains a variable component based on a percentage of revenue. The following table summarizes the fixed and variable components of the Company’s operating leases ($ in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Fixed ground rent expense	$	390	$	185	$	1,108	$	321
Variable ground rent expense		—		26		21		56
Total cash portion of ground rent expense		390		211		1,129		377
Non-cash ground rent expense		1,091		98		3,275		256
Total operating lease costs	$	1,481	$	309	$	4,404	$	633

The following table summarizes the fixed and variable components of the Company’s financing leases ($ in thousands).

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Interest on lease liabilities	$	737	$	—	$	1,491	$	—
Amortization of right-of-use assets		243		—		504		—
Total financing lease costs	$	980	$	—	$	1,995	$	—

Lease costs recognized during the prior periods are presented under the standard in effect prior to the Company’s adoption of ASU 2016-02.

The Company’s rental revenue primarily consists of rent earned from operating leases at the Company’s multifamily, industrial, retail, and other properties. Leases at the Company’s industrial and retail properties generally include a fixed base rent and certain leases also contain a variable component. The variable component of the Company’s operating leases at its industrial and retail properties primarily consist of the reimbursement of operating expenses such as real estate taxes, insurance, and common area maintenance costs. Leases at the Company’s industrial and retail properties are generally longer term and may contain extension and termination options at the lessee’s election. Rental revenue earned from leases at the Company’s multifamily properties primarily consist of a fixed base rent and certain leases contain a variable component that allows for the pass-through of certain operating expenses such as utilities. Leases at the Company’s multifamily and other properties are short term in nature, generally not greater than 12 months in length.

The following table details the components of operating lease income from leases in which the Company is the lessor ($ in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Fixed lease payments	$	262,043	$	134,567	$	674,780	$	323,334
Variable lease payments		28,410		18,271		75,542		42,879
Rental revenue	$	290,453	$	152,838	$	750,322	$	366,213

The following table presents the undiscounted future minimum rents the Company expects to receive for its industrial and retail properties ($ in thousands). Leases at the Company’s multifamily and self-storage properties are short term, generally 12 months or less, and are therefore not included.

Year	Future Minimum Rents
2019 (remaining)	$	144,099
2020		555,279
2021		490,102
2022		403,061
2023		309,951
2024		227,048
Thereafter		578,598
Total	$	2,708,138

The following table presents the future minimum rents the Company expects to receive for its industrial and retail properties as of December 31, 2018, prior to the adoption of ASU 2016-02 ($ in thousands):

Year	Future Minimum Rents
2019	$	238,043
2020		215,327
2021		185,419
2022		144,186
2023		102,609
Thereafter		285,981
Total	$	1,171,565