Mortgage backed securities Mortgage backed securities designated as Trading (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading Securities, Debt	$ 29,808		$ 30,069
Trading Securities, Amortized cost	27,381		27,535
Trading Securities, Unrealized Holding Loss	$ (107)	$ (136)

Debt securities that are bought and held principally for the purpose of selling them in the near term (thus held for only a short period of time) or for debt securities formerly categorized as available-for-sale or held-to-maturity which the entity held as of the date it opted to account for such securities at fair value. An enterprise may also categorize such a security as trading without the intent to sell it in the near term assuming the decision to categorize the security as trading occurred at acquisition.

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+ Details

- Definition

The increase (decrease) resulting in a loss from the difference between the fair value and the carrying value, or in the comparative fair values, of trading securities held at each balance sheet date, that was included in earnings for the period.

+ References

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

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-Publisher FASB

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+ Details