Derivative Financial Instruments (Fair value hedges) (Gains (losses) recognized) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Fair value hedges \| Interest income
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss)	$ 894	$ 194

Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

Name:	us-gaap_GainLossOnFairValueHedgesRecognizedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration