Investment Securities, Available-for-sale Securities (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	$ 763,910	$ 893,821
Gross Unrealized Gains	588	467
Gross Unrealized Losses	23,206	30,534
Total securities available for sale	741,292	863,754
U. S. government sponsored enterprises [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	93,805	200,531
Gross Unrealized Gains	39	22
Gross Unrealized Losses	1,136	1,724
Total securities available for sale	92,708	198,829
State and political subdivisions [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	4,862	7,623
Gross Unrealized Gains	106	135
Gross Unrealized Losses	0	0
Total securities available for sale	4,968	7,758
Mortgage-backed securities and collateralized mortgage obligations-residential [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	538,002	552,230
Gross Unrealized Gains	442	267
Gross Unrealized Losses	14,247	20,048
Total securities available for sale	524,197	532,449
Corporate bonds [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	6,403	10,429
Gross Unrealized Gains	1	43
Gross Unrealized Losses	2	1
Total securities available for sale	6,402	10,471
Small Business Administration-guaranteed participation securities [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	109,280	111,383
Gross Unrealized Gains	0	0
Gross Unrealized Losses	7,459	8,354
Total securities available for sale	101,821	103,029
Mortgage-backed securities and collateralized mortgage obligations-Commercial [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	10,898	10,965
Gross Unrealized Gains	0	0
Gross Unrealized Losses	355	407
Total securities available for sale	10,543	10,558
Other [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	650	650
Gross Unrealized Gains	0	0
Gross Unrealized Losses	7	0
Total securities available for sale	643	650
Debt securities [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	763,900	893,811
Gross Unrealized Gains	588	467
Gross Unrealized Losses	23,206	30,534
Total securities available for sale	741,282	863,744
Equity securities [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	10	10
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Total securities available for sale	$ 10	$ 10

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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