Summary of Other Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Nonoperating Income Expense [Abstract]
Interest expense	$ (13,615)	$ (7,335)
Interest income	2,139	2,361
Amortization of investment discount	2,964	4,332
Gain from sale of Priority Review Voucher	108,069
Other income	1,092	470
Total other income (loss)	$ 100,649	$ (172)