Goodwill (Key Ratios to Measure Goodwill of Bank Reporting Unit for Impairment) (Detail) (Bank Reporting Unit [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
May 31, 2012 Ratios	Mar. 31, 2013
Goodwill [Line Items]
Key ratios considered in measuring the fair value of the bank reporting unit	2
Goodwill	$ 1,158,248	$ 1,165,200
Fair value of the bank reporting unit exceeded carrying value	5.90%
Annual [Member]
Goodwill [Line Items]
Price to book	1.29
Price to tangible book	1.47

Carrying amount of goodwill allocated to the bank reporting unit.

No definition available.

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Key Ratios Considered In Measuring The Fair Value Of The Bank Reporting Unit

No definition available.

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Market multiple used, in part, to determine the fair value of the bank reporting unit.

No definition available.

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Namespace Prefix:	susq_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Market multiple used, in part, to determine the fair value of the bank reporting unit.

No definition available.

Name:	susq_MarketMultipleUsedToDetermineFairValueOfBankReportingUnitPriceToTangibleBook
Namespace Prefix:	susq_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Percentage By Which Fair Value Of Bank Reporting Unit Exceeded Its Carrying Value

No definition available.

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Namespace Prefix:	susq_
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Period Type:	instant