Deposits (Schedule of Deposits) (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deposit [Line Items]
Non-interest-bearing demand deposits:	$ 10,997,494	$ 11,197,093
Time Deposits, $100,000 or More	531,121
Total Interest-bearing deposits	16,151,710	15,675,296
Total deposits	27,149,204	26,872,389
Commercial And Individual [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	10,305,850	10,412,882
Correspondent Banks [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	235,748	222,648
Private Accounts [Member]
Deposit [Line Items]
Savings and interest checking	6,977,813	6,788,766
Money market accounts	7,777,470	7,624,471
Time Deposits, $100,000 or More	526,789	453,668
Time accounts under $100,000	331,511	324,636
Total private accounts	15,613,583	15,191,541
Public Funds [Member]
Deposit [Line Items]
Non-interest-bearing demand deposits:	455,896	561,563
Savings and interest checking	473,754	410,140
Money market accounts	59,953	59,008
Time Deposits, $100,000 or More	4,332	14,301
Time accounts under $100,000	88	306
Total public funds	$ 538,127	$ 483,755

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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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