Significant Accounting Policies - Additional Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Accounting Policies [Abstract]
Cash paid for interest		$ 31,712	$ 66,657
Cash paid for income taxes		32,174	31,858
Unsettled securities transactions		216,855	39,896
Loans foreclosed and transferred to other real estate owned and foreclosed assets		0	616
Loans to facilitate the sale of other real estate owned		0	847
Right-of-use lease assets obtained in exchange for lessee operating lease liabilities		18,679	295,109
Stock Issued During Period, Value, Treasury Stock Reissued	$ 2,830	$ 2,830	$ 0