2.Significant Balance Sheet Components

Accounts Receivable, Net —Accounts receivable, net at March 31, 2018 and December 31, 2017 consisted of the following (in thousands):


	March 31, 2018		December 31, 2017
Accounts receivable - billed	$	34,208	$	48,646
Accounts receivable - unbilled		1,872		2,458
Allowance for doubtful accounts		(475)		(475)
Accounts receivable, net	$	35,605	$	50,629

Property and Equipment —Property and equipment at March 31, 2018 and December 31, 2017 consisted of the following (in thousands):


	March 31, 2018		December 31, 2017
Computers and appliances	$	12,732	$	13,178
Purchased software		4,224		4,063
Furniture and fixtures		1,737		1,734
Leasehold improvements		3,229		3,226
Total property and equipment		21,922		22,201
Accumulated depreciation and amortization		(13,717)		(13,389)
Total property and equipment—net	$	8,205	$	8,812

Accrued Expenses —Accrued expenses at March 31, 2018 and December 31, 2017 consisted of the following (in thousands):


	March 31, 2018		December 31, 2017
Accrued commissions	$	2,775	$	3,989
Accrued stock-settled bonus		2,469		7,705
Employee Stock Purchase Plan liability		778		2,047
Other accrued payroll-related expenses		3,383		4,285
Other accrued liabilities		6,714		7,044
Total accrued expenses	$	16,119	$	25,070