The aggregate expected value at the end of their useful life of a major finite-lived intangible asset class acquired during the period either individually or as part of a group of assets (in either an asset acquisition or business combination). A major class is composed of intangible assets that can be grouped together because they are similar, either by their nature or by their use in the operations of a company.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16265-109275

Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2017
Amortized intangible assets - core deposits [Abstract]
Gross Carrying Amount			$ 11,916	$ 6,118
Accumulated Amortization			5,207	4,532
Unamortized intangible assets - goodwill [Abstract]
Gross Carrying Amount	$ 28,300	$ 0	28,300	$ 0
Increases in gross carrying amount of core deposit intangibles		5,800
Increases (decrease) in goodwill	(700)	$ 28,300
Expected residual value of core deposit intangible asset			0
Expected amortization period of core deposit intangible asset		10 years
Weighted average amortization period of core deposit intangible asset		5 years 2 months 12 days
Summary of estimated intangible amortization [Abstract]
Three months ending December 31, 2018			293
2019			1,089
2020			1,020
2021			970
2022			785
2023 and thereafter			2,552
Total			$ 6,709
Goodwill [Roll Forward]
Balance at beginning of year		$ 0
Acquired during the year		28,300
Balance at end of the period	$ 28,300	$ 28,300