Capitalized Software Development Costs, Net - Summary of Capitalized Software Development Costs, Net (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Capitalized Computer Software Net [Line Items]
Gross carrying amount	$ 47,820	$ 45,677
Accumulated amortization	(33,728)	(32,784)
Net carrying amount	14,092	12,893
Capitalized Software Development Costs
Capitalized Computer Software Net [Line Items]
Gross carrying amount	$ 47,820	$ 45,677
Amortization period	3 years	3 years
Accumulated amortization	$ (33,728)	$ (32,784)
Net carrying amount	$ 14,092	$ 12,893