4. Acquired Intangible Assets and Liabilities

Summarized below are the carrying values for the major classes of intangible assets and liabilities (in thousands):


		December 31, 2018						December 31, 2017
	Useful Lives	Gross Carrying Value		Accumulated Amortization		Net Carrying Value		Gross Carrying Value		Accumulated Amortization		Net Carrying Value
Customer Relationships	12 years	$	95,705	$	(28,461)	$	67,244	$	95,705	$	(20,512)	$	75,193
In-Place Leases	0.5 to 10 years		32,066		(17,670)		14,396		32,066		(12,987)		19,079
Solar Power Agreement (1)	17 years		13,747		(3,639)		10,108		13,747		(2,830)		10,917
Platform Intangible	3 years		9,600		(9,600)		—		9,600		(8,133)		1,467
Acquired Favorable Leases
Acquired below market leases - as Lessee	46 years		2,301		—		2,301		—		—		—
Acquired above market leases - as Lessor	0.5 to 8 years		4,649		(3,247)		1,402		4,649		(2,328)		2,321
Tradenames	3 years		3,100		(3,100)		—		3,100		(2,626)		474
Total Intangible Assets		$	161,168	$	(65,717)	$	95,451	$	158,867	$	(49,416)	$	109,451

Solar Power Agreement (1)	17 years		13,747		(3,639)		10,108		13,747		(2,830)		10,917
Acquired Unfavorable Leases
Acquired below market leases - as Lessor	3 to 4 years		809		(611)		198		809		(375)		434
Acquired above market leases - as Lessee	11 to 12 years		2,453		(767)		1,686		2,453		(550)		1,903
Total Intangible Liabilities (2)		$	17,009	$	(5,017)	$	11,992	$	17,009	$	(3,755)	$	13,254

(1)

Amortization related to the Solar Power Agreement asset and liability is recorded at the same rate and therefore has no net impact on the statement of operations.

(2)

Intangible liabilities are included within the “Advance rents, security deposits and other liabilities” line item of the consolidated balance sheets.

Above or below market leases are amortized as a reduction to or increase in rental revenue in the case of the Company as lessor as well as a reduction to or increase in rent expense in the case of the Company as lessee over the remaining lease terms. The net effect of amortization of acquired above‑market and below‑market leases resulted in a net decrease in rental revenue of $0.5 million, $0.9 million, and $0.7 million for the years ended December 31, 2018, 2017 and 2016, respectively. The estimated amortization of acquired favorable and unfavorable leases for each of the five succeeding fiscal years ending December 31 is as follows (in thousands):


	Net Rental Revenue Decreases		Net Rental Expense Increase / (Decrease)
2019	$	479	$	(166)
2020		647		(166)
2021		46		(166)
2022		17		(166)
2023		17		(166)
Thereafter		—		1,446
Total	$	1,205	$	615

Net amortization of all other identified intangible assets and liabilities was $15.0 million, $18.2 million and $19.0 million for the years ended December 31, 2018, 2017 and 2016, respectively. The estimated net amortization of all other identified intangible assets and liabilities for each of the five succeeding fiscal years ending December 31 is as follows (in thousands):


2019	$	11,965
2020		11,379
2021		10,137
2022		9,910
2023		9,910
Thereafter		28,339
Total	$	81,640