Investment Securities - Securities with gross unrealized losses - (Details 4) $ in Thousands	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)
Investment Securities
Number of securities with gross unrealized loss \| item	90
Securities Available for Sale, Gross Unrealized Losses
Less Than Twelve Months	$ 3,326	$ 367
Twelve Months or More	1,219	3,274
Securities Available for Sale, Fair Value
Less Than Twelve Months	439,359	85,848
Twelve Months or More	45,470	148,565
Government-sponsored entities debt
Securities Available for Sale, Gross Unrealized Losses
Less Than Twelve Months	717	98
Twelve Months or More	392	1,616
Securities Available for Sale, Fair Value
Less Than Twelve Months	88,224	22,896
Twelve Months or More	17,598	82,798
State and municipal obligations
Securities Available for Sale, Gross Unrealized Losses
Less Than Twelve Months	9	3
Twelve Months or More	105	192
Securities Available for Sale, Fair Value
Less Than Twelve Months	3,755	1,444
Twelve Months or More	2,650	8,269
Mortgage-backed securities.
Securities Available for Sale, Gross Unrealized Losses
Less Than Twelve Months	2,600	266
Twelve Months or More	430	774
Securities Available for Sale, Fair Value
Less Than Twelve Months	347,380	61,508
Twelve Months or More	23,772	55,960
Common Stock
Securities Available for Sale, Gross Unrealized Losses
Twelve Months or More	292	692
Securities Available for Sale, Fair Value
Twelve Months or More	$ 1,450	$ 1,538

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months.

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This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Topic 320
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-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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