Income Taxes - Reconciliation of Unrecognized Tax Benefit Balances (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, Beginning Balance	$ 22,590	$ 22,625	$ 22,919
Gross increases for tax positions of prior years	0	516	93
Gross decreases for tax positions of prior years	(99)	0	(31)
Gross increases for tax positions of current year	60	0	0
Purchase accounting for 1st Global Acquisition	442	0	0
Settlements with taxing authorities	(563)	0	(66)
Statute of limitations expirations	(2,947)	(551)	(290)
Unrecognized tax benefits, Ending Balance	$ 19,483	$ 22,590	$ 22,625