We lease substantially all our hotels to a wholly owned subsidiary that qualifies as a taxable REIT subsidiary due to the U.S. federal income tax prohibition on the ability of a REIT to derive revenues directly from the operations of a hotel.

As of December 31, 2019, all or a portion of 22 of our hotels are subject to ground leases, generally with multiple renewal options, all of which are accounted for as operating leases. Payments for ground leases account for approximately 76% of our 2019 minimum lease payments and 95% of our total future minimum lease payments. For lease agreements with scheduled rent increases, we recognize the fixed portion of the lease expense ratably over the term of the lease. As the exercise of the renewal options were determined to be reasonably certain, the payments associated with the renewals have been included in the measurement of the lease liability and ROU asset. Contingent rental payments based on a percentage of sales in excess of stipulated amounts are not included in the measurement of the lease liability and ROU asset but will be recognized as variable lease expense if and when they are incurred. However, certain of these leases contain provisions that increase the minimum lease payments based on an average of the variable lease payments made over the previous years, for which we will reevaluate the lease liability and ROU asset as these payments now represent an increase in the minimum payments for the remainder of the lease term. Certain of these leases also contain provisions that increase the minimum lease payments based on an index such as the Consumer Price Index. Subsequent to the initial adoption of the new standard, such amounts are not included in the measurement of the lease liability and ROU asset but will be recognized as variable lease expense if and when they are incurred. The discount rate used to calculate the lease liability and ROU asset is based on our incremental borrowing rate (“IBR”), as the rate implicit in each lease is not readily determinable. To calculate our IBR, we obtained a forward curve using LIBOR swap rates, with terms ranging from one to fifty years, as well as corresponding bond spreads based on the terms of the leases and our credit risk. The resulting discount rates for our ground leases range from 4.3% to 5.7%.

We have office leases for our headquarters office in Bethesda, which expires in 2036, as well as satellite offices in Miami and San Diego, which leases expire in 2022 and 2021, respectively, with no renewal options.

We also have leases on facilities used in our former restaurant business, all of which we subsequently subleased. These leases and subleases contain one or more renewal options, generally for five- or ten-year periods. The restaurant leases are accounted for as operating leases. Our contingent liability related to these leases is $5 million as of December 31, 2019. We, however, consider the likelihood of any material funding related to these leases to be remote. Our leasing activity also includes leases entered into by our hotels for various types of equipment that have been accounted for historically either as operating or capital leases, depending upon the characteristics of the particular lease arrangement. As we have elected to use the package of practical expedients, all existing capital leases now are classified as finance leases, which total $1 million at December 31, 2019.

As disclosed in Note 1 – Summary of Significant Accounting Policies, we adopted ASU No. 2016-02, Leases (Topic 842), as amended, using the effective date transition method. As a result, disclosures required under the new standard will not be provided for dates or periods prior to January 1, 2019. For the comparative periods, we will provide disclosures required by ASC 840, Leases.

	Year ended December 31,
	2019
Lease cost
Operating lease cost	$	47
Variable lease cost		36
Sublease income		(1	)
Total lease cost	$	82

Other information
Operating cash flows used for operating leases for the year ended December 31, 2019	$	47
Weighted-average remaining lease term - operating leases	50 years
Weighted-average discount rate - operating leases		5.3	%

The following table presents a reconciliation of the total amount of lease payments, on an undiscounted basis, to the lease liability in the statement of financial position as of December 31, 2019 (in millions):

	As of December 31, 2019
	Ground Leases			Office Leases and Other			Total
Weighted-average discount rate - operating leases		5.4	%		3.6	%		5.3	%
2020	$	32		$	7		$	39
2021		32			6			38
2022		32			6			38
2023		32			4			36
2024		32			4			36
Thereafter		1,530			56			1,586
Total undiscounted cash flows	$	1,690		$	83		$	1,773

Present values
Long-term lease liabilities	$	543		$	63		$	606
Total lease liabilities	$	543		$	63		$	606
Difference between undiscounted cash flows and discounted cash flows	$	1,147		$	20		$	1,167

Minimum payments for the operating leases have not been reduced by aggregate minimum sublease rentals from restaurants of approximately $5 million that are payable to us under non-cancelable subleases. The following table presents the future minimum annual rental commitments, excluding renewal periods, as of December 31, 2018, for which we are the lessee, required under non-cancelable operating leases in accordance with ASC 840, under which we report prior to January 1, 2019 (in millions):

	As of December 31, 2018
2019	$	46
2020		44
2021		43
2022		40
2023		37
Thereafter		1,309
Total minimum lease payments	$	1,519

Rent expense in accordance with ASC 840, under which we report prior to January 1, 2019, consists of (in millions):

	Year ended December 31,
	2018			2017
Minimum rentals on operating leases	$	45		$	46
Additional rentals based on sales		38			38
Less: sublease rentals		(1	)		(1	)
	$	82		$	83