Securities (Securities Available for Sale) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	$ 1,981,977	$ 2,087,069
Available-for-sale Debt Securities Gross Unrealized Gain, instant	31,790	25,527
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(6,608)	(14,339)
Securities available for sale	2,007,159us-gaap_AvailableForSaleSecurities	2,098,257us-gaap_AvailableForSaleSecurities
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	1,093,576	1,160,378
Available-for-sale Debt Securities Gross Unrealized Gain, instant	13,765	10,219
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(4,641)	(8,210)
Securities available for sale	1,102,700	1,162,387
State and Municipal Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	486,969	483,578
Available-for-sale Debt Securities Gross Unrealized Gain, instant	15,434	14,432
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(732)	(1,526)
Securities available for sale	501,671	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	375,230	416,919
Available-for-sale Debt Securities Gross Unrealized Gain, instant	2,551	856
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(983)	(4,069)
Securities available for sale	376,798	413,706
US Government Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities available-for-sale, amortized cost	20,918	20,910
Available-for-sale Debt Securities Gross Unrealized Gain, instant	0	0
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(140)	(411)
Securities available for sale	20,778	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	40	20
Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax	(112)	(123)
Securities available for sale	$ 5,212	$ 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

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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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