Financial Instruments (Available-for-sale Debt Securities) - Additional Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, debt securities, par value	$ 59,100	$ 55,700
Available-for-sale debt securities, maturity start date	2019-10
Available-for-sale debt securities, maturity end date	2024-02
Funds held for clients	$ 123,448	161,289
Certified Deposits and Other Depository Assets [Member]
Schedule Of Available For Sale Securities [Line Items]
Funds held for clients	$ 2,300	$ 2,300