Investment Securities - Amortized Cost and Fair Values of Debt Securities Held to Maturity (Details) $ in Thousands	Dec. 31, 2015 USD ($)
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 384,324
Gross Unrealized Gains	331
Gross Unrealized Losses	(2,314)
Estimated Fair Value	382,341
Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	31,910
Gross Unrealized Gains	301
Gross Unrealized Losses	(58)
Estimated Fair Value	32,153
Mortgage - Backed Securities - Residential [Member] \| US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	4,775
Gross Unrealized Gains	0
Gross Unrealized Losses	(7)
Estimated Fair Value	4,768
Mortgage - Backed Securities - Residential [Member] \| Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	315,609
Gross Unrealized Gains	30
Gross Unrealized Losses	(1,824)
Estimated Fair Value	313,815
Mortgage - Backed Securities - Commercial [Member] \| US Government Agencies Debt Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	16,843
Gross Unrealized Gains	0
Gross Unrealized Losses	(247)
Estimated Fair Value	16,596
Mortgage - Backed Securities - Commercial [Member] \| Obligations of U.S. Government-Sponsored Enterprises [Member]
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	15,187
Gross Unrealized Gains	0
Gross Unrealized Losses	(178)
Estimated Fair Value	$ 15,009

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=28360136&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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