Deposits (Schedule of Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deposit [Line Items]
Non-interest-bearing demand deposits:	$ 10,873,629	$ 10,997,494
Time Deposits, $100,000 or More	761,153
Total Interest-bearing deposits	16,765,935	16,151,710
Total deposits	27,639,564	27,149,204
Commercial And Individual [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	10,212,265	10,305,850
Correspondent Banks [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	246,181	235,748
Private Accounts [Member]
Deposit [Line Items]
Savings and interest checking	7,147,327	6,977,813
Money market accounts	7,888,433	7,777,470
Time Deposits, $100,000 or More	736,481	526,789
Time accounts under $100,000	347,418	331,511
Total private accounts	16,119,659	15,613,583
Public Funds [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	415,183	455,896
Savings and interest checking	548,399	473,754
Money market accounts	73,180	59,953
Time Deposits, $100,000 or More	24,672	4,332
Time accounts under $100,000	25	88
Total public funds	$ 646,276	$ 538,127

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Interest Bearing Deposits Public Funds

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- Definition

Interest Bearing Private Accounts Deposits

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- Definition

The aggregate of all deposit liabilities held by the entity, including foreign and domestic, interest and noninterest bearing; may include demand deposits, saving deposits, Negotiable Order of Withdrawal (NOW) and time deposits among others.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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Amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.

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The aggregate of all domestic and foreign interest-bearing deposit liabilities.

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The aggregate amount of all domestic and foreign noninterest-bearing deposits liabilities held by the entity.

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Amount of time deposit liabilities, including certificates of deposit, in denominations of $100,000 or more.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher SEC
-Name Industry Guide
-Number 3
-Section V
-Paragraph D-E

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Amount of time deposit liabilities, including certificates of deposit, in denominations of less than $100,000.

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