Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Name:	us-gaap_Goodwill
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Goodwill - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Goodwill - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2016	Jun. 30, 2017	May 19, 2017	Dec. 31, 2015
Goodwill [Line Items]
Goodwill		$ 244,000	$ 292,188		$ 243,129
Goodwill, measurement period adjustment		$ 871
Arlington Bank
Goodwill [Line Items]
Goodwill				$ 48,188
Ameriana
Goodwill [Line Items]
Goodwill					$ 38,624
Goodwill, measurement period adjustment	$ 871