6. Property and equipment

The following is a summary of property and equipment, at cost less accumulated depreciation and amortization:

	December 31,
	2017			2016
Leasehold improvements	$	418,023		$	358,477
Software		42,281			33,349
Construction in progress		27,291			18,859
Computer equipment		13,245			10,878
Furniture, fixtures and office equipment		1,806			1,760

Total property and equipment		502,646			423,323
Less: accumulated depreciation and amortization		(240,287	)		(172,558	)

Total property and equipment, net	$	262,359		$	250,765

Included in property and equipment at December 31, 2017 and 2016 was equipment acquired under capital leases totaling $12,714 and $8,780, respectively, and related accumulated depreciation and amortization of $3,744 and $2,352, respectively.

Depreciation and amortization expense, which includes depreciation and amortization for property and equipment under capital leases, is allocated on a specific identification basis as follows on the accompanying consolidated statements of operations:

	For the Years Ended December 31,
	2017		2016		2015
Network access	$	42,435	$	27,013	$	22,666
Network operations		16,382		13,966		9,058
Development and technology		9,247		7,207		5,441
General and administrative		1,033		1,016		1,128

Total depreciation and amortization of property and equipment	$	69,097	$	49,202	$	38,293

During the years ended December 31, 2017, 2016, and 2015 we recognized $882, $54, and $215, respectively, of impairment losses primarily related to construction in progress projects that were abandoned. During the year ended December 31, 2017, we also recognized $276 of losses on disposals of property and equipment.