Disposals (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Jun. 30, 2014
Disposals [Abstract]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal	$ 4.4
Loans in disposal	27.9oksb_AssetsOfDisposalGroup
Deposits in disposal	$ 130.6oksb_LiabilitiesOfDisposalGroup

The gain (loss) resulting from the sale of a disposal group that is not a discontinued operation. It is included in income from continuing operations before income taxes in the income statement.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6360339&loc=d3e1361-107760

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=8077374&loc=d3e2443-110228

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration