Property, net:

Property at December 31, 2018 and 2017 consists of the following:



	2018			2017
Land	$	1,506,678		$	1,567,152
Buildings and improvements	6,288,308			6,385,035
Tenant improvements	678,110			620,352
Equipment and furnishings	206,398			187,998
Construction in progress	199,326			366,996
	8,878,820			9,127,533
Less accumulated depreciation	(2,093,044		)	(2,018,303		)
	$	6,785,776		$	7,109,230

Depreciation expense for the years ended December 31, 2018, 2017 and 2016 was $275,236, $277,917 and $277,270, respectively.

The loss on the sale or write down of assets, net for the year ended December 31, 2018 includes a loss of $54,469 on impairment, $28,266 on the write off of development costs and $311 on the sale of Promenade at Casa Grande (See Note 15—Dispositions). These losses were offset in part by a gain of $46,242 on the sale of a 75% ownership interest in One Westside (See Note 4—Investments in Unconsolidated Joint Ventures) and $4,989 on the sale of land parcels. The loss on impairment was due to the reduction of the estimated holding periods of SouthPark Mall, La Cumbre Plaza, Southridge Center and Promenade at Casa Grande.

The gain on sale or write down of assets, net for the year ended December 31, 2017 includes a gain of $59,577 on the sale of Cascade Mall and Northgate Mall (See Note 15—Dispositions), $14,597 on the sale of 500 North Michigan Avenue (See Note 15—Dispositions) and $1,564 on the sales of land. These gains were offset in part by a loss of $22,108 on impairment, $10,138 on the write down of an investment in non-real estate assets and $1,046 on the write off of development costs. The loss on impairment was due to the reduction of the estimated holding periods of Southridge Center and Promenade at Casa Grande.

The gain on sale or write down of assets, net for the year ended December 31, 2016 includes a gain of $101,629 on the sale of a 40% ownership interest in Arrowhead Towne Center (See Note 4—Investments in Unconsolidated Joint Ventures), $340,734 on the sale of a 49% ownership interest in the MAC Heitman Portfolio (See Note 4—Investments in Unconsolidated Joint Ventures), $24,894 on the sale of Capitola Mall (See Note 15—Dispositions) and $4,546 on the sale of land. These gains were offset in part by a loss of $39,671 on impairment, a charge of $12,180 from a contingent consideration obligation, a loss of $3,066 on the sale of a former Mervyn's store (See Note 15—Dispositions) and $1,538 on the write-off of development costs. The loss on impairment was due to the reduction of the estimated holding periods of Cascade Mall, Promenade at Casa Grande, The Marketplace at Flagstaff and a freestanding store.

The following table summarizes certain of the Company's assets that were measured on a nonrecurring basis as a result of impairment charges recorded for the years ended December 31, 2018, 2017 and 2016 as described above:



Years ended December, 31	Total Fair Value Measurement		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Years ended December, 31	Total Fair Value Measurement		(Level 1)		(Level 2)		(Level 3)
2018	$	104,700	$	—	$	104,700	$	—
2017	$	38,000	$	—	$	38,000	$	—
2016	$	86,100	$	—	$	—	$	86,100

The fair value relating to impairments that were based on sales contracts were classified within Level 2 of the fair value hierarchy. The fair value relating to impairment assessments that were not based on sales contracts were based on a discounted cash flow model that included all cash inflows and outflows over a specific holding period. Such projected cash flows are comprised of contractual rental revenues and forecasted rental revenues and expenses based upon market conditions and expectations for growth. Terminal capitalization rates and discount rates utilized in these models are based on a reasonable range of current market rates for each property analyzed. Based upon these inputs, the Company determined that its valuations of properties using a discounted cash flow model are classified within Level 3 of the fair value hierarchy.

The following table sets forth quantitative information about the unobservable inputs of the Company’s Level 3 real estate recorded as of December 31, 2016:



Terminal capitalization rate			7.0% - 10.0%
Discount rate			8.0% - 15.0%
Market rents per square foot			$2.00 - $20.00