Investment Securities, Available-for-sale Securities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	$ 893,821	$ 905,846
Gross Unrealized Gains	467	6,903
Gross Unrealized Losses	30,534	657
Total securities available for sale	863,754	912,092
U. S. government sponsored enterprises [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	200,531	262,063
Gross Unrealized Gains	22	1,055
Gross Unrealized Losses	1,724	10
Total securities available for sale	198,829	263,108
State and political subdivisions [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	7,623	25,815
Gross Unrealized Gains	135	642
Gross Unrealized Losses	0	0
Total securities available for sale	7,758	26,457
Mortgage-backed securities and collateralized mortgage obligations-residential [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	552,230	515,322
Gross Unrealized Gains	267	3,982
Gross Unrealized Losses	20,048	528
Total securities available for sale	532,449	518,776
Corporate bonds [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	10,429	26,312
Gross Unrealized Gains	43	336
Gross Unrealized Losses	1	119
Total securities available for sale	10,471	26,529
Small Business Administration-guaranteed participation securities [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	111,383	75,674
Gross Unrealized Gains	0	888
Gross Unrealized Losses	8,354	0
Total securities available for sale	103,029	76,562
Mortgage-backed securities and collateralized mortgage obligations-Commercial [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	10,965
Gross Unrealized Gains	0
Gross Unrealized Losses	407
Total securities available for sale	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	0	0
Total securities available for sale	650	650
Debt securities [Member]
Amortized cost and fair value of the securities available for sale [Abstract]
Amortized Cost	893,811	905,836
Gross Unrealized Gains	467	6,903
Gross Unrealized Losses	30,534	657
Total securities available for sale	863,744	912,082
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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