Summary of Significant Accounting Policies (Additional Cash Flow Information) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash paid for interest	$ 124,781	$ 89,270	$ 24,371
Cash paid for income tax	45,352	5,112	56,359
Transfer of investment securities to held to maturity from available for sale	377,812	0	0
Unsettled purchases/sales of securities	0	330	37,481
Loans foreclosed and transferred to other real estate owned and foreclosed assets	1,348	2,899	279
Loans to facilitate the sale of other real estate owned	847	0	0
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 319,286	$ 0	$ 0