Deferred Costs, Acquired Lease Intangibles and Goodwill

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



	2015			2014
Leasing costs	$	121,864		$	100,653
Acquired in-place lease value and deferred leasing costs	285,902			304,916
Acquired above-market leases	81,680			84,633
	489,446			490,202
Less: accumulated amortization	(178,767		)	(132,740		)
Total deferred costs, net	$	310,679		$	357,462

Amortization expense related to deferred leasing and acquired deferred leasing costs was $25.4 million, $21.9 million, and $10.6 million, for the years ended December 31, 2015, 2014, and 2013, respectively. Amortization expense related to acquired lease intangibles was $37.7 million, $33.7 million and $5.3 million for the years ended December 31, 2015, 2014 and 2013, respectively.

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



	2015			2014
Acquired below-market ground leases	$	396,916		$	396,916
Less: accumulated amortization	(13,025		)	(5,029		)
Acquired below-market ground leases, net	$	383,891		$	391,887



	2015			2014
Acquired below-market leases	$	(163,290	)	$	(169,805	)
Less: accumulated amortization	59,119			30,946
Acquired below-market leases, net	$	(104,171	)	$	(138,859	)

Rental revenue related to the amortization of below market leases, net of above market leases was $19.4 million, $14.1 million and $1.9 million for the years ended December 31, 2015, 2014 and 2013, respectively. The remaining weighted-average amortization period as of December 31, 2015 is 26.0 years, 4.9 years, 4.0 years and 4.5 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
2016	$	7,831	$	32,756	$	9,283
2017	7,831		25,331		5,658
2018	7,831		19,298		6,338
2019	7,831		16,534		6,552
2020	7,831		13,389		3,453
Thereafter	344,736		64,027		18,643
	$	383,891	$	171,335	$	49,927

As of December 31, 2015, 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.