Deposits Composition (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Deposits And Customer Funding By Type [Abstract]
Noninterest-bearing demand deposits	$ 4,505,272	$ 4,626,312
Savings deposits	1,235,277us-gaap_DepositsSavingsDeposits	1,159,512us-gaap_DepositsSavingsDeposits
Interest-bearing demand deposits	3,126,854	2,889,705
Money market deposits	8,324,646us-gaap_DepositsMoneyMarketDeposits	6,906,442us-gaap_DepositsMoneyMarketDeposits
Brokered certificates of deposit	42,556asb_BrokeredCertificatesOfDeposit	50,450asb_BrokeredCertificatesOfDeposit
Other time deposits	1,528,899asb_OtherTimeDeposits	1,634,746asb_OtherTimeDeposits
Total deposits	$ 18,763,504us-gaap_Deposits	$ 17,267,167us-gaap_Deposits

Brokered certificates of deposit.

No definition available.

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- Definition

Other time deposits

+ References

No definition available.

+ Details

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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://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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 12

-Article 9

+ Details

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- Details

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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

+ Details

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- Definition

Amount of deposits in interest-bearing transaction accounts at banks or savings and loans, that are restricted in regard to ownership and can usually only be held by individuals, nonprofit entities and governments. Negotiable order of withdrawal accounts differ from money market demand accounts as they typically have higher reserve requirements and no limit on the number of checks that can be written.

+ References

+ Details

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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).

+ References

+ Details

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Period Type:	instant

- Definition

Amount of money in noninterest-bearing domestic accounts that entitle the depositor to withdraw funds at any time without prior notice, also known as demand deposits.

+ References

+ Details

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