Investment Securities - Amortized Cost and Fair Value of Available for Sale Securities and Held to Maturity Securities by Contractual Maturity (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Available for Sale
Due in one year or less - Amortized Cost	$ 11,621
Due after one through five years - Amortized Cost	27,954
Due after five through ten years - Amortized Cost	47,657
Due after ten years - Amortized Cost	182,700
Total debt securities with a single maturity date - Amortized Cost	269,932
Total Investment Securities - Amortized Cost	597,967
Due in one year or less - Fair Value	11,769
Due after one through five years - Fair Value	28,496
Due after five through ten years - Fair Value	48,830
Due after ten years - Fair Value	184,169
Total debt securities with a single maturity date - Fair Value	273,264
Total Investment Securities - Fair Value	605,507
Held to Maturity
Due in one year or less - Amortized Cost	3,867
Due after one through five years - Amortized Cost	17,378
Due after five through ten years - Amortized Cost	78,688
Due after ten years - Amortized Cost	44,854
Total debt securities with a single maturity date - Amortized Cost	144,787
Total Investment Securities - Amortized Cost	544,470	559,378
Due in one year or less - Fair Value	3,867
Due after one through five years - Fair Value	17,633
Due after five through ten years - Fair Value	79,407
Due after ten years - Fair Value	45,829
Total debt securities with a single maturity date - Fair Value	146,736
Investment securities held to maturity - fair value	551,621	560,847
U.S. Government-sponsored mortgage-backed securities
Available for Sale
Without single maturity date - Amortized Cost	326,329
Without single maturity date - Fair Value	330,537
Held to Maturity
Without single maturity date - Amortized Cost	399,683
Total Investment Securities - Amortized Cost	399,683	413,437
Without single maturity date - Fair Value	404,885
Investment securities held to maturity - fair value	404,885	414,935
Equity securities
Available for Sale
Without single maturity date - Amortized Cost	1,706
Without single maturity date - Fair Value	$ 1,706

Available-For-Sale Securities, Debt Maturity, with Single Maturity Date, Amortized Cost

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Available-For-Sale Securities, Debt Maturity, with Single Maturity Date, Fair Value

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized and fair value hedge accounting adjustments, maturing in the next rolling twelve months following the latest balance sheet presented.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized and fair value hedge accounting adjustments, maturing after the tenth rolling twelve months following the latest balance sheet presented.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized and fair value hedge accounting adjustments, maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized and fair value hedge accounting adjustments, maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented

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Held-To-Maturity Securities, Debt Maturities, with Single Maturity Date, Net Carrying Amount

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Held-To-Maturity Securities, Debt Maturity, with Single Maturity Date, Fair Value

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Amount of available-for-sale debt securities at cost, net of adjustments, which include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the next rolling twelve months following the latest balance sheet presented.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing after the tenth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing after the tenth rolling twelve months following the latest balance sheet presented.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented.

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Amount of available-for-sale debt securities at cost, net of adjustments, that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the cost over several maturity groupings. Adjustments include, but are not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized in earnings (less any cumulative-effect adjustments, as defined) and fair value hedge accounting adjustments.

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Amount of available-for-sale debt securities at fair value that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the fair value over several maturity groupings.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount of held-to-maturity debt securities at fair value maturing in the next rolling twelve months following the latest balance sheet presented.

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Amount of held-to-maturity debt securities at fair value maturing after the tenth rolling twelve months following the latest balance sheet presented.

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Amount of held-to-maturity debt securities at fair value maturing in the sixth rolling twelve months through the tenth rolling twelve months following the latest balance sheet presented.

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Amount of held-to-maturity debt securities at fair value maturing in the second rolling twelve months through the fifth rolling twelve months following the latest balance sheet presented.

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Amount of held-to-maturity debt securities at fair value that do not have a single maturity date and which the entity has decided to disclose separately rather than allocating the fair value over several maturity groupings.

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Carrying amount of debt securities accounted for as held-to-maturity, net of adjustments including, but not limited to, accretion, amortization, collection of cash, previous other-than-temporary impairments (OTTI) recognized, and fair value hedge accounting adjustments, over several maturity groupings.

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Fair value of investments in debt securities classified as held-to-maturity.

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