Deferred Costs

9 Months Ended

Sep. 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 nine months ended September 30, 2020 are as follows (in thousands):

	As of December 31, 2019				Expense recognized		As of September 30, 2020
			Additions
Deferred commissions	$	14,718	$	1,396	$	(5,517)	$	10,597
Deferred professional service costs	6,711		983		(2,417)		5,277
Total deferred commissions and professional service costs	$	21,429	$	2,379	$	(7,934)	$	15,874

    These costs are reviewed for impairment quarterly. Impairment charges were $0.2 million and $0.2 million for the three months ended September 30, 2020 and 2019, respectively, and were $1.5 million and $0.8 million for the nine months ended September 30, 2020 and 2019, respectively.