Investment Securities - Debt Maturities (Details) (Investment Securities [Member], USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Investment Securities [Member]
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Amortized Cost	$ 1,246,490
Available-for-sale Securities, Due after one year through five years, Amortized Cost	288,599
Available-for-sale Securities, Due after five years through ten years, Amortized Cost	325,128
Available-for-sale Securities, Due after ten years, Amortized Cost	612,851
Available-for-sale Securities, Amortized Cost Basis	2,473,068	2,485,421
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Fair Value	1,246,691
Available-for-sale Securities, Due after one year through five years, Fair Value	289,722
Available-for-sale Securities, Due after five years through ten years, Fair Value	323,229
Available-for-sale Securities, Due after ten years, Fair Value	609,450
Available-for-sale securities	$ 2,469,092	$ 2,483,147
Available-for-sale Securities, Debt Maturities, Weighted-Average Yield, Fiscal Year Maturity [Abstract]
Available-for-sale Securities, Due within one year, Weighted-Average Yield	0.43%
Available-for-sale Securities, Due after one year through five years, Weighted-Average Yield	0.84%
Available-for-sale Securities, Due after five years through ten years, Weighted-Average Yield	0.79%
Available-for-sale Securities, Due after ten years, Weighted-Average Yield	2.35%
Available-for-sale Securities, Total Weighted-Average Yield	1.00%

Available-for-sale Securities, Debt Maturities, after Ten Years, Weighted-Average Yield

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- Definition

Available-for-sale Securities, Debt Maturities, Next Twelve Months, Weighted-Average Yield

+ References

No definition available.

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- Definition

Available-for-sale Securities, Debt Maturities, Weighted-Average Yield

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- Definition

Available-for-sale Securities, Debt Maturities, Year Six Through Ten, Weighted-Average Yield

+ References

No definition available.

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- Definition

Available-for-sale Securities, Debt Maturities, Year Two Through Five, Weighted-Average Yield

+ References

No definition available.

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

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-Name Accounting Standards Codification

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- Definition

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.

+ References

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- Definition

Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year. 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.

+ References

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- Definition

Amount of available-for-sale debt securities at fair value maturing in the sixth fiscal year through the tenth fiscal year following the latest fiscal year.

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- Definition

Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year. 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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- Definition

Amount of available-for-sale debt securities at fair value maturing in the second fiscal year through the fifth fiscal year following the latest fiscal year.

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Amount of available-for-sale debt securities at cost, net of adjustments, maturing after the tenth fiscal year following the latest fiscal year. 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 fiscal year following the latest fiscal year.

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- Definition

Amount of available-for-sale debt securities at cost, net of adjustments, maturing in the next fiscal year following the latest fiscal year. 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 next fiscal year following the latest fiscal year.

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