Related-Party Transactions - Relationship with HOV Services, Ltd (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related-Party Transactions
Amount of related party transaction													$ 9,501	$ 12,403	$ 33,431
Related party expense	$ 1,742	$ 1,430	$ 5,331	$ 998	$ 3,664	$ 775	$ 6,783	$ 1,181	$ 6,329	$ 7,964	$ 7,759	$ 8,739	9,501	12,403	33,431
HOV Services, Ltd | Data Capture And Technology Services | Cost of revenue
Related-Party Transactions
Amount of related party transaction													$ 1,500	$ 1,600	$ 1,700