Deferred Costs

6 Months Ended

Jun. 30, 2020

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Deferred Costs

Deferred Costs

Changes in the balance of total deferred commissions and total deferred professional service costs during the six months ended June 30, 2020 are as follows (in thousands):

	As of December 31, 2019				Expense recognized		As of June 30, 2020
			Additions
Deferred commissions	$	14,718	$	920	$	(3,919)	$	11,719
Deferred professional service costs	6,711		663		(1,657)		5,717
Total deferred commissions and professional service costs	$	21,429	$	1,583	$	(5,576)	$	17,436

 These costs are reviewed for impairment quarterly. Impairment charges were $0.2 million and $1.3 million for the three and six months ended June 30, 2020, respectively. Impairment charges for the three and six months ended June 30, 2019 were immaterial.