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Mortgage Banking Derivatives (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mortgage Banking Derivatives
Amount of loans sold to investors	$ 147,700
Proceeds from sale of loan to investors	151,289	$ 197,654	$ 196,431
Gain on sale of loan	4,803	6,343	$ 5,775
Fair market valuation gain	1,300
Federal National Mortgage Association
Mortgage Banking Derivatives
Amount of loans sold to investors	$ 88,900
Federal National Mortgage Association | Customer concentration risk
Mortgage Banking Derivatives
Percentage of concentration risk	60.30%
Wells Fargo | Customer concentration risk
Mortgage Banking Derivatives
Percentage of concentration risk	19.60%
Federal Home Loan Mortgage Corp.
Mortgage Banking Derivatives
Amount of loans sold to investors	$ 28,900
Not designated | Forward MBS contracts and forward loan contracts
Mortgage Banking Derivatives
Notional or Contractual Amount	16,500	19,500
Fair value	3	190
Not designated | Rate Lock Commitments
Mortgage Banking Derivatives
Notional or Contractual Amount	10,478	12,480
Fair value	$ 235	$ 97

X

- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Represents the amount of loans held for sale, sold during the period.

+ References

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Fair value of the assets less the liabilities of a derivative or group of derivatives.

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

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The cash inflow resulting from the sale of loans classified as held-for-sale, including proceeds from loans sold through mortgage securitization.

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