Investment Securities (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Proceeds	$ 14,913	$ 4,027	$ 72,262
Gross realized gains	1,574fdef_MarketableSecuritiesRealizedGain	97fdef_MarketableSecuritiesRealizedGain	2,163fdef_MarketableSecuritiesRealizedGain
Gross realized losses	$ (642)fdef_MarketableSecuritiesRealizedLoss	$ 0fdef_MarketableSecuritiesRealizedLoss	$ (24)fdef_MarketableSecuritiesRealizedLoss

The cash inflow associated with the aggregate amount received by the entity through sale or maturity of marketable securities (held-to-maturity or available-for-sale) during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=6871852&loc=d3e26853-111562

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (a),(b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromSaleAndMaturityOfMarketableSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration