Deposits Deposits (Summary of Deposits) (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Balance:
Non-interest bearing	$ 3,779,609	$ 3,518,685	$ 2,773,922
NOW and interest bearing demand deposits	2,262,928	2,236,089	1,983,251
Wealth management deposits	1,528,963wtfc_WealthManagementDeposits	1,226,916wtfc_WealthManagementDeposits	1,289,134wtfc_WealthManagementDeposits
Money market	3,791,762us-gaap_DepositsMoneyMarketDeposits	3,651,467us-gaap_DepositsMoneyMarketDeposits	3,454,271us-gaap_DepositsMoneyMarketDeposits
Savings	1,563,752us-gaap_DepositsSavingsDeposits	1,508,877us-gaap_DepositsSavingsDeposits	1,443,943us-gaap_DepositsSavingsDeposits
Time certificates of deposit	4,011,755us-gaap_TimeDeposits	4,139,810us-gaap_TimeDeposits	4,184,524us-gaap_TimeDeposits
Total deposits	$ 16,938,769us-gaap_Deposits	$ 16,281,844us-gaap_Deposits	$ 15,129,045us-gaap_Deposits
Mix:
Non-interest bearing	22.00%wtfc_NonInterestBearingPercentage	22.00%wtfc_NonInterestBearingPercentage	18.00%wtfc_NonInterestBearingPercentage
NOW and interest bearing demand deposits	13.00%	14.00%	13.00%
Wealth management deposits	9.00%wtfc_WealthManagementDepositsPercentage	8.00%wtfc_WealthManagementDepositsPercentage	8.00%wtfc_WealthManagementDepositsPercentage
Money market	23.00%	22.00%	23.00%
Savings	9.00%	9.00%	10.00%
Time certificates of deposit	24.00%	25.00%	28.00%
Total deposits	100.00%wtfc_DepositsPercentage	100.00%wtfc_DepositsPercentage	100.00%wtfc_DepositsPercentage

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.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-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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- Definition

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.

+ References

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- Definition

Amount of interest bearing deposits with no stated maturity, which may include passbook and statement savings accounts and money-market deposit accounts (MMDAs).

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- Definition

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

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- Definition

Percentage of interest-bearing domestic money market demand account deposit liabilities to total deposit liabilities.

+ References

No definition available.

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- Definition

Percentage of interest-bearing domestic savings deposit liabilities to total deposit liabilities.

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- Definition

Percentage of interest-bearing domestic time deposit liabilities to total deposit liabilities.

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- Definition

Amount of deposits that cannot be withdrawn before a set date without penalty or for which notice of withdrawal is required. Time deposits include, but are not limited to, certificates of deposits, individual retirement accounts and open accounts.

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- Definition

Deposits, NOW and Interest Bearing Demand Deposits

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Deposits, Percentage

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- Definition

Non-interest bearing, percentage

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NOW and Interest Bearing Demand Deposits Percentage

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- Definition

Wealth management deposits

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Wealth management deposits, percentage

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