Dispositions and Impairment

For the years ended December 31, 2018, 2017 and 2016, the Company disposed of its interests in certain properties generating aggregate net proceeds of $898,514, $223,853 and $370,038, respectively, which resulted in gains on sales of $252,913, $63,428 and $81,510, respectively, including, in 2018, the disposition of 21 office assets to a newly-formed joint venture, NNN Office JV L.P. (“NNN JV”), with an unaffiliated third-party. See note 7. For the years ended December 31, 2018, 2017 and 2016, the Company recognized net debt satisfaction gains (charges) relating to properties sold of $(1,698), $5,938 and $(532), respectively. The Company had two properties classified as held for sale at December 31, 2018 and one property classified as held for sale at December 31, 2017.

Assets and liabilities of held for sale properties as of December 31, 2018 and 2017 consisted of the following:



	December 31, 2018			December 31, 2017
Assets:
Real estate, at cost	$	63,639		$	2,827
Real estate, intangible assets	14,498			—
Accumulated depreciation and amortization	(16,873		)	—
Rent receivable - deferred	2,439			—
Other	165			—
	$	63,868		$	2,827
Liabilities:
Other	$	386		$	—
	$	386		$	—

The Company assesses on a regular basis whether there are any indicators that the carrying value of real estate assets may be impaired. Potential indicators may include an increase in vacancy at a property, tenant financial instability, change in the estimated holding period of an asset and the potential sale of the property in the near future. An asset is determined to be impaired if the asset's carrying value is in excess of its estimated fair value and the Company estimates that its cost will not be recovered. During 2018, 2017 and 2016, the Company recognized aggregate impairment charges on real estate properties of $95,813, $39,702 and $100,195, respectively. During 2018, $36,620 of the impairment charges of $95,813 were recognized on properties owned at December 31, 2018. The Company's office assets in Overland Park, Kansas and Kansas City, Missouri incurred an aggregate $23,496 of impairment charges due to a reduction in the anticipated holding period and leasing prospects. During 2017, $18,023 of the impairment charges of $39,702 were recognized on properties held at December 31, 2017. The Company's office asset in Florence, South Carolina and industrial asset in Memphis, Tennessee incurred an aggregate $15,008 of the impairment charges due to a reduction in anticipating holding period. The 2016 impairment charges include an aggregate impairment charge of $65,500 recognized on the sale of three land investments in New York, New York.

In February 2017, the Company recognized a $5,294 loan loss on the assignment of a loan receivable secured by a hospital in Kennewick, Washington.