Securities (Securities Available for Sale) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	$ 2,004,728	$ 2,087,069
Available-for-sale Debt Securities Gross Unrealized Gain, instant	29,138	25,527
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(6,442)	(14,339)
Securities available for sale	2,027,424	2,098,257
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	1,157,054	1,160,378
Available-for-sale Debt Securities Gross Unrealized Gain, instant	12,610	10,219
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(5,132)	(8,210)
Securities available for sale	1,164,532	1,162,387
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	476,650	483,578
Available-for-sale Debt Securities Gross Unrealized Gain, instant	13,574	14,432
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(755)	(1,526)
Securities available for sale	489,469	496,484
U.S. Government and Government-Sponsored Enterprise Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	345,309	416,919
Available-for-sale Debt Securities Gross Unrealized Gain, instant	2,922	856
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(375)	(4,069)
Securities available for sale	347,856	413,706
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	20,431	20,910
Available-for-sale Debt Securities Gross Unrealized Gain, instant	1	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(32)	(411)
Securities available for sale	20,400	20,499
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	31	20
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(148)	(123)
Securities available for sale	$ 5,167	$ 5,181

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)

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Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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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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Amount before tax of unrealized loss 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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