Components of Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Component Of Other Expense Income Nonoperating [Line Items]
Interest expense	$ (3,041)	$ (839)	$ (9,633)	$ (1,984)
Interest income on term deposits	189	1,972	414	9,457
Gain on sale of mutual funds, net	276	2,983	847	5,462
Miscellaneous income	55	111	217	263
Other income (expense), net	$ (2,521)	$ 4,227	$ (8,155)	$ 13,198