Fair Value Measurements - Additional Quantitative Information (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Quantitative Information about Level 3 Fair Value Measurements
Impaired loans	$ 44,432	$ 36,717
Non-recurring basis
Quantitative Information about Level 3 Fair Value Measurements
Impaired loans	3,301	3,885
OREO	16
Non-recurring basis \| Level 3
Quantitative Information about Level 3 Fair Value Measurements
Impaired loans	3,301	3,885
OREO	16
Non-recurring basis \| Level 3 \| Appraisal of collateral \| Impaired loans
Quantitative Information about Level 3 Fair Value Measurements
Impaired loans	$ 3,301	$ 3,885
Non-recurring basis \| Level 3 \| Appraisal of collateral \| Impaired loans \| Minimum
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(21.30%)	(19.20%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| Impaired loans \| Maximum
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(100.00%)	(100.00%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| Impaired loans \| Weighted Average
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(32.60%)	(38.40%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| OREO
Quantitative Information about Level 3 Fair Value Measurements
OREO	$ 16
Appraisal adjustments (as a percent)		(100.00%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| OREO \| Minimum
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(71.90%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| OREO \| Maximum
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(100.00%)
Non-recurring basis \| Level 3 \| Appraisal of collateral \| OREO \| Weighted Average
Quantitative Information about Level 3 Fair Value Measurements
Appraisal adjustments (as a percent)	(88.40%)	(100.00%)

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Percentage of adjustment to the observed price for a similar asset or liability when an identical transaction does not exist, used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 14A
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=SL6953550-111524

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Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 10
-Section S99
-Paragraph 6
-Subparagraph (SX 210.5-04(c)(Schedule III))
-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 970
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