Property, Plant and Equipment, and Leases

Property, plant and equipment by type were as follows:



(in thousands)	As of December 31,
							2015			2014
Property, Plant and Equipment	2017			2016			(Restated)			(Restated)
Land	$	—		$	—		$	260		$	260
Buildings	—			—			1,471			1,471
Leasehold improvements	6,320			6,199			6,450			3,333
Machinery and equipment	27,379			24,490			23,523			17,500
Construction in progress	2,036			2,084			2,466			3,566
Total property, plant and equipment, at cost	35,735			32,773			34,170			26,130
Accumulated depreciation	(16,775		)	(12,646		)	(11,361		)	(8,176		)
Property, plant and equipment, net	$	18,960		$	20,127		$	22,809		$	17,954

Property, plant and equipment in 2016 includes a noncash conversion of inventory of $1.1 million purchased prior to 2016.

Leases

The Company leases certain buildings and equipment under various non-cancelable operating leases and a capital lease. Rent expense under operating leases approximated $4.7 million, $5.2 million, $4.9 million and $3.6 million for 2017, 2016, 2015 and 2014, respectively. Rent expense is recorded on a straight-line basis over the period of the lease term. The Company recognized the capital lease obligation of $0.4 million and related leased equipment based on the present value of the minimum lease payments at lease inception.

The future minimum lease payments due under operating and capital leases in effect, as amended and extended, as of December 31, 2017, were as follows:



(in thousands)	Operating		Capital
2018	$	4,341	$	22
2019	4,136		21
2020	3,786		20
2021	3,482		20
2022	3,578		19
2023 and beyond	3,202		51
Total	$	22,525	$	153

In July 2018, the Company entered into the first and second lease amendments for two industrial buildings located in Wood Dale, Illinois. The extended terms of the lease amendments are from August 1, 2018 through and including July 31, 2023. These buildings are used for manufacturing, warehousing and certain administrative functions. Total base rental payments over these extended periods are $9.4 million and are included in the future minimum lease payments above.

In December 2018, the Company entered into a new lease agreement for an industrial building located in Hanover Park, Illinois. The terms of the lease are from January 1, 2019 through and including July 31, 2023. This building is used primarily for operations, storage and certain administrative functions. Total base rental payments over the life of the lease are $4.2 million, which are not included in the future minimum lease payments above.