NOTE 9. Intangibles

The Company’s intangible lease assets were (in thousands):


	December 31,
Intangible lease assets	2014		2013
Lease-up intangibles	$	608,323	$	578,143
Above market tenant lease intangibles		163,146		144,355
Below market ground lease intangibles		58,939		58,939
Gross intangible lease assets		830,408		781,437
Accumulated depreciation and amortization		(349,395)		(291,595)
Net intangible lease assets	$	481,013	$	489,842

The remaining weighted average amortization period of intangible assets were 14 and 15 years at December 31, 2014 and 2013, respectively.

The Company’s intangible lease liabilities were (in thousands):


	December 31,
Intangible lease liabilities	2014		2013
Below market lease intangibles	$	203,374	$	201,234
Above market ground lease intangibles		6,121		6,121
Gross intangible lease liabilities		209,495		207,355
Accumulated depreciation and amortization		(124,772)		(108,545)
Net intangible lease liabilities	$	84,723	$	98,810

The remaining weighted average amortization period of unfavorable market lease intangibles was approximately 9 years at both December 31, 2014 and 2013.

For the years ended December 31, 2014, 2013 and 2012, rental income includes additional revenues of $3 million, $9 million and $4 million, respectively, from the amortization of net below market lease intangibles. For the years ended December 31, 2014, 2013 and 2012, operating expenses include additional expense of $1 million each year from the amortization of net above market ground lease intangibles. For the years ended December 31, 2014, 2013 and 2012, depreciation and amortization expense includes additional expense of $60 million, $59 million and $44 million, respectively, from the amortization of lease-up and non-compete agreement intangibles.

Estimated aggregate amortization of intangible assets and liabilities for each of the five succeeding fiscal years and thereafter follows (in thousands):


	Intangible		Intangible
	Assets		Liabilities
2015	$	78,168	$	17,069
2016		73,480		16,528
2017		61,252		14,101
2018		46,403		11,406
2019		34,929		8,800
Thereafter		186,781		16,819
	$	481,013	$	84,723