8.	OTHER ASSETS

Other assets consist of the following (in thousands):

	December 31,
	2017		2016
Debt issuance costs, less accumulated amortization of $2,711 and $1,633, respectively	$	2,518	$	3,526
Intangible lease value, less accumulated amortization of $6,920 and $4,990, respectively		34,668		36,598
Other intangible assets, less accumulated amortization of $2,625 and $1,421, respectively		8,585		4,434
Deferred leasing costs		6,738		7,380
Cash equivalents and cash surrender value of life insurance held in Rabbi trust		13,537		13,110
Straight-line rent receivable		9,335		9,229
Other		13,337		8,725
	$	88,718	$	83,002

The gross carrying amount of intangible assets amounted to $52.8 million and $47.4 million at December 31, 2017 and 2016, respectively. Of these amounts, $41.6 million was related to intangible lease values at both December 31, 2017 and 2016. Amortization expense related to intangible assets was $3.4 million, $2.9 million, and $1.5 million for 2017, 2016, and 2015, respectively, and depending upon the nature of the asset, was either reported as operating expense or depreciation and amortization in the accompanying statement of operations for the respective periods.

As of December 31, 2017, the estimated amortization expense related to intangible assets for each of the next five years is as follows (in thousands):

2018	$	4,307
2019		4,014
2020		3,423
2021		2,562
2022		1,687