Note 2: Available-for-sale Securities: Other Securities Policy: Pooled Trust Preferred Securities (Details) - Jun. 30, 2015 $ in Thousands	USD ($)
Details
Number of Pooled Trust Preferred Securities	3
Fair Value of Pooled Trust Preferred Securities Held	$ 770,000
Unrealized Losses on Pooled Trust Preferred Securities in a Continuous Unrealized Loss Position for 12 Months or More	$ 662,000

Represents the monetary amount of Unrealized Losses on Pooled Trust Preferred Securities in a Continuous Unrealized Loss Position for 12 Months or More, as of the indicated date.

No definition available.

Name:	smbc_UnrealizedLossesOnPooledTrustPreferredSecuritiesInAContinuousUnrealizedLossPositionFor12MonthsOrMore
Namespace Prefix:	smbc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant