Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Balance at beginning of period	$ 147,445	$ 113,486
Additions based on tax positions related to the current year	19,287	30,811
(Deletions) Additions for tax positions of prior years	2,016	3,148
Balance at end of period	$ 168,748	$ 147,445