Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Forward contracts
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) realized due to changes in fair value of loans	$ 80	$ (2,700)
Noninterest income \| Residential mortgage loans held for sale
Fair Value, Option, Quantitative Disclosures [Line Items]
Net gains (losses) realized due to changes in fair value of loans	$ (173)	$ 1,300

For each line item in the statement of financial position, the amounts of gains and losses from fair value changes included in earnings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=75031198&loc=d3e14172-108612

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration