Securities (Amortized Cost and Fair Value of Securities Available for Sale) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	$ 2,116,271	$ 2,086,745
Securities Available for Sale, Gross Unrealized Gains	34,408	20,120
Securities Available for Sale, Gross Unrealized Losses	1,213	13,461
Securities Available for Sale, Fair Value	2,149,466	2,093,404
US Treasury and Government Agency Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	125	135
Securities Available for Sale, Gross Unrealized Losses		1
Securities Available for Sale, Fair Value	125	134
Municipal Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	87,190	39,410
Securities Available for Sale, Gross Unrealized Gains	792	235
Securities Available for Sale, Gross Unrealized Losses	43	38
Securities Available for Sale, Fair Value	87,939	39,607
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	1,735,836	1,750,168
Securities Available for Sale, Gross Unrealized Gains	30,862	19,387
Securities Available for Sale, Gross Unrealized Losses	724	11,182
Securities Available for Sale, Fair Value	1,765,974	1,758,373
Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	287,171	291,085
Securities Available for Sale, Gross Unrealized Gains	2,414	140
Securities Available for Sale, Gross Unrealized Losses	419	2,192
Securities Available for Sale, Fair Value	289,166	289,033
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	3,500	3,500
Securities Available for Sale, Fair Value	3,500	3,500
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities Available for Sale, Amortized Cost	2,449	2,447
Securities Available for Sale, Gross Unrealized Gains	340	358
Securities Available for Sale, Gross Unrealized Losses	27	48
Securities Available for Sale, Fair Value	$ 2,762	$ 2,757

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=51813488&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=27724398&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=49167202&loc=d3e26610-111562

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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-SubTopic 10
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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
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