Supplemental Consolidated Balance Sheet Information - Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Accrued Liabilities and Other Liabilities [Abstract]
Accrued vacation	$ 10,824	$ 8,353
Accrued commissions	5,570	5,561
Accrued bonuses	7,999	7,121
Estimated health insurance claims	1,076	1,040
ESPP employee contributions	3,862	3,734
Customer deposits	13,526	12,151
Operating lease liabilities	4,385	3,064
Accrued other liabilities	9,145	8,906
Accrued expenses and other current liabilities	$ 56,387	$ 49,930