Securities (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	$ 2,156,999	$ 2,157,610
Available-for-sale Debt Securities Gross Unrealized Gain, instant	33,588	18,352
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(4,421)	(18,268)
Securities available for sale	2,186,166	2,157,694
U.S. Government Agency and Government-Sponsored Enterprise Mortgage-Backed Securities and Collateralized Mortgage Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	1,319,714	1,296,955
Available-for-sale Debt Securities Gross Unrealized Gain, instant	14,247	4,525
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(3,861)	(14,991)
Securities available for sale	1,330,100	1,286,489
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	477,544	480,417
Available-for-sale Debt Securities Gross Unrealized Gain, instant	14,257	12,690
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(414)	(938)
Securities available for sale	491,387	492,169
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	353,910	354,515
Available-for-sale Debt Securities Gross Unrealized Gain, instant	5,031	1,113
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(1,846)
Securities available for sale	358,941	353,782
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	547	20,439
Available-for-sale Debt Securities Gross Unrealized Gain, instant	0	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	0	(302)
Securities available for sale	547	20,137
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	5,284	5,284
Available-for-sale Debt Securities Gross Unrealized Gain, instant	53	24
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(146)	(191)
Securities available for sale	$ 5,191	$ 5,117

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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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563

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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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-Topic 320
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-Subparagraph (c)
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.2)
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