Investment Securities Held to Maturity Securities by Type (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	$ 396,444	$ 384,324
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	4,525	331
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(5)	(2,314)
Securities held to maturity, fair value	400,964	382,341
US Government Agencies Residential Mortgage-backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	4,743	4,775
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	99	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	(7)
Securities held to maturity, fair value	4,842	4,768
US Government Agency Debt Securities Commercial [Domain]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	16,767	16,843
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	0	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(3)	(247)
Securities held to maturity, fair value	16,764	16,596
Residential Mortgage Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	325,974	315,609
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	3,526	30
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	(1,824)
Securities held to maturity, fair value	329,500	313,815
Obligations of U.S. Government-Sponsored Enterprises - Mortgage-Backed Securities - Commercial [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	15,067	15,187
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	273	0
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	0	(178)
Securities held to maturity, fair value	15,340	15,009
Obligations of States and Political Subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity Securities	33,893	31,910
Held-to-maturity Securities, Accumulated Unrecognized Holding Gain	627	301
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	(2)	(58)
Securities held to maturity, fair value	$ 34,518	$ 32,153

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27232-111563

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1)
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.6)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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