Fair Value Measurements (Details 4) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Valuation Methodology
Investment securities, available-for-sale	$ 850,467	$ 791,727
Level 3
Valuation Methodology
Investment securities, available-for-sale	3,506	5,337
Recurring \| Level 3
Valuation Methodology
Investment securities, available-for-sale	3,506	5,337
Recurring \| Level 3 \| Discounted cash flows \| Direct placement municipal securities
Valuation Methodology
Investment securities, available-for-sale	$ 2,699	$ 4,528
Recurring \| Level 3 \| Discounted cash flows \| Direct placement municipal securities \| Minimum
Unobservable Inputs
Credit spread assumption (as a percent)	0.92%	1.27%
Recurring \| Level 3 \| Discounted cash flows \| Direct placement municipal securities \| Maximum
Unobservable Inputs
Credit spread assumption (as a percent)	3.17%	2.03%
Recurring \| Level 3 \| Discounted cash flows \| Foreign government
Valuation Methodology
Investment securities, available-for-sale	$ 807	$ 809
Recurring \| Level 3 \| Discounted cash flows \| Foreign government \| Minimum
Unobservable Inputs
Market yield assumption (as a percent)	0.28%	0.88%
Recurring \| Level 3 \| Discounted cash flows \| Foreign government \| Maximum
Unobservable Inputs
Market yield assumption (as a percent)	1.12%	2.00%
Non-recurring \| Level 3 \| Commercial loans
Unobservable Inputs
Discount rate (as a percent)	20.00%
Non-recurring \| Level 3 \| Minimum \| Commercial loans
Unobservable Inputs
Discount rate (as a percent)	40.00%	40.00%
Non-recurring \| Level 3 \| Maximum \| Commercial loans
Unobservable Inputs
Discount rate (as a percent)	75.00%	75.00%
Non-recurring \| Level 3 \| Trade publications \| Aircraft
Unobservable Inputs
Discount rate (as a percent)	10.00%
Non-recurring \| Level 3 \| Auction values \| Autos
Unobservable Inputs
Discount rate (as a percent)	10.00%
Non-recurring \| Level 3 \| Trade publications and auction values \| Medium and heavy duty trucks
Unobservable Inputs
Discount rate (as a percent)	15.00%
Non-recurring \| Level 3 \| Trade publications and auction values \| Construction equipment
Unobservable Inputs
Discount rate (as a percent)	20.00%
Non-recurring \| Level 3 \| Appraisals \| Real estate
Unobservable Inputs
Discount rate (as a percent)	20.00%

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=65884222&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=66010992&loc=d3e26610-111562

+ Details

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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisValuationTechniquesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_FairValueInputsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of adjustment to the observed price for a similar asset or liability when an identical transaction does not exist, used as an input to measure fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsComparabilityAdjustments
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

+ References

+ Details

Name:	us-gaap_FairValueInputsDiscountForLackOfMarketability
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Risk associated with risk of default, credit spread risk and downgrade risk, expressed as a percentage, used as an input to measure fair value.

+ References

+ Details

Name:	us-gaap_FairValueInputsEntityCreditRisk
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of likelihood a loan will not be repaid and instead default, used as an input to measure fair value.

+ References

+ Details

Name:	us-gaap_FairValueInputsProbabilityOfDefault
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration