Deferred Costs, Acquired Lease Intangibles and Goodwill

Deferred costs, net, consisted of the following at December 31, 2017 and 2016 (amounts in thousands):



	2017			2016
Leasing costs	$	164,751		$	140,325
Acquired in-place lease value and deferred leasing costs	237,364			253,113
Acquired above-market leases	67,415			74,770
	469,530			468,208
Less: accumulated amortization	(215,102		)	(195,617		)
Total deferred costs, net, excluding net deferred financing costs	$	254,428		$	272,591

At December 31, 2017 and 2016, $8.3 million and $4.5 million, respectively, of net deferred financing costs associated with the unsecured revolving credit facility was included in deferred costs, net on the consolidated balance sheets.

Amortization expense related to deferred leasing and acquired deferred leasing costs was $24.1 million, $24.2 million, and $25.4 million, for the years ended December 31, 2017, 2016, and 2015, respectively. Amortization expense related to acquired lease intangibles was $17.1 million, $24.6 million and $37.7 million for the years ended December 31, 2017, 2016 and 2015, respectively.

Amortizing acquired intangible assets and liabilities consisted of the following at December 31, 2017 and 2016 (amounts in thousands):



	2017			2016
Acquired below-market ground leases	$	396,916		$	396,916
Less: accumulated amortization	(28,687		)	(20,856		)
Acquired below-market ground leases, net	$	368,229		$	376,060



	2017			2016
Acquired below-market leases	$	(132,026	)	$	(135,026	)
Less: accumulated amortization	65,979			52,726
Acquired below-market leases, net	$	(66,047	)	$	(82,300	)

Rental revenue related to the amortization of below market leases, net of above market leases was $5.7 million, $8.8 million and $19.4 million for the years ended December 31, 2017, 2016 and 2015, respectively. The remaining weighted-average amortization period as of December 31, 2017 is 25.0 years, 4.8 years, 3.9 years and 4.2 years for below-market ground leases, in-place leases and deferred leasing costs, above-market leases and below-market leases, respectively. We expect to recognize amortization expense and rental revenue from the acquired intangible assets and liabilities as follows (amounts in thousands):



For the year ending:	Future Ground Rent Amortization		Future Amortization Expense		Future Rental Revenue
2018	$	7,831	$	18,650	$	6,442
2019	7,831		15,996		6,689
2020	7,831		13,046		3,559
2021	7,831		11,302		2,857
2022	7,831		10,485		3,175
Thereafter	329,074		41,549		12,690
	$	368,229	$	111,028	$	35,412

As of December 31, 2017, we had goodwill of $491.5 million. In 2013, we acquired the interests in Empire State Building Company, L.L.C. and 501 Seventh Avenue Associates, L.L.C. for an amount in excess of their net tangible and identified intangible assets and liabilities and as a result we recorded goodwill related to the transaction. Goodwill was allocated $227.5 million to the observatory operations of the Empire State Building, $250.8 million to Empire State Building, and $13.2 million to 501 Seventh Avenue.

We performed an annual review of goodwill for impairment and concluded there was no impairment of goodwill. Our methodology to review goodwill impairment, which includes a significant amount of judgment and estimates, provides a reasonable basis to determine whether impairment has occurred. However, many of the factors employed in determining whether or not goodwill is impaired are outside of our control and it is reasonably likely that assumptions and estimates will change in future periods.