PROPERTY, PLANT AND EQUIPMENT

The following is a summary of the Company’s property, plant, and equipment:



	December 31,
(In Thousands)	2017			2016
Land	$	19,768		$	22,843
Buildings and Improvements	67,053			69,935
Leasehold Improvements and Signs	69,407			75,786
Fixtures and Equipment¹	266,761			247,565
Assets Under Capital Leases:
with Related Parties	4,032			10,573
with Unrelated Parties	12,426			11,063
Construction in Progress	10,863			4,568
	450,310			442,333
Less: Accumulated Depreciation and Amortization	(242,623		)	(231,062		)
	$	207,687		$	211,271


¹	Includes internal-use software development costs of $86.2 million and $73.0 million as of December 31, 2017 and 2016, respectively. Accumulated amortization of internal-use software development costs amounted to $42.6 million and $31.1 million as of December 31, 2017 and 2016, respectively.

Amortization expense on assets recorded under capital leases is included in operating expenses and was $1.5 million, $1.7 million and $1.7 million for the years ended December 31, 2017, 2016 and 2015, respectively. Capital leases primarily consist of buildings and improvements, as well as vehicles assumed as part of the SEI acquisition. Assets under capital leases with related parties included $3.6 million and $9.0 million in accumulated depreciation and amortization as of December 31, 2017 and 2016, respectively. Assets under capital leases with unrelated parties included $4.7 million and $6.9 million in accumulated depreciation and amortization as of December 31, 2017 and 2016, respectively.