Other Income, net - Summary of Other Income, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Nonoperating Income (Expense) [Abstract]
Gain on sale and mark-to-market of mutual funds	$ 12,965	$ 9,970	$ 8,766
Interest and dividend income	2,399	1,873	1,625
Others, net	1,143	1,146	968
Other income, net	$ 16,507	$ 12,989	$ 11,359