Investment Securities (Schedule of Securities Classified as Current and Long-Term) (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Available for sale securities amortized cost	$ 8,898,540	$ 8,175,981
Available for sale securities gross unrealized gains	326,819	258,465
Available for sale securities gross unrealized losses	(22,703)	(62,007)
Available for sale securities fair value	9,202,656	8,372,439
Debt Securities [Member] \| U.S. Treasury and Government [Member] \| U.S. Treasury and Agency Obligations [Member]
Available for sale securities amortized cost	808,985	697,816
Available for sale securities gross unrealized gains	14,242	14,412
Available for sale securities gross unrealized losses	(440)	(615)
Available for sale securities fair value	822,787	711,613
Debt Securities [Member] \| U.S. Treasury and Government [Member] \| Mortgage-Backed Securities [Member]
Available for sale securities amortized cost	1,761,438	1,614,569
Available for sale securities gross unrealized gains	63,358	49,783
Available for sale securities gross unrealized losses	(760)	(1,173)
Available for sale securities fair value	1,824,036	1,663,179
Debt Securities [Member] \| Tax-Exempt Municipal Securities [Member]
Available for sale securities amortized cost	2,437,115	2,439,659
Available for sale securities gross unrealized gains	63,506	37,294
Available for sale securities gross unrealized losses	(10,738)	(43,619)
Available for sale securities fair value	2,489,883	2,433,334
Debt Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Available for sale securities amortized cost	50,858	58,017
Available for sale securities gross unrealized gains	425	545
Available for sale securities gross unrealized losses	(1,534)	(2,675)
Available for sale securities fair value	49,749	55,887
Debt Securities [Member] \| Commercial Mortgage-Backed Securities [Member]
Available for sale securities amortized cost	397,262	306,291
Available for sale securities gross unrealized gains	18,618	14,911
Available for sale securities gross unrealized losses	(917)	(171)
Available for sale securities fair value	414,963	321,031
Debt Securities [Member] \| Asset-Backed Securities [Member]
Available for sale securities amortized cost	115,928	148,068
Available for sale securities gross unrealized gains	1,486	1,727
Available for sale securities gross unrealized losses	(29)	(44)
Available for sale securities fair value	117,385	149,751
Debt Securities [Member] \| Corporate Debt Securities [Member]
Available for sale securities amortized cost	3,321,621	2,906,228
Available for sale securities gross unrealized gains	165,184	139,793
Available for sale securities gross unrealized losses	(8,285)	(13,710)
Available for sale securities fair value	3,478,520	3,032,311
Debt Securities [Member] \| Redeemable Preferred Stock [Member]
Available for sale securities amortized cost	5,333	5,333
Available for sale securities gross unrealized gains	0	0
Available for sale securities gross unrealized losses	0	0
Available for sale securities fair value	$ 5,333	$ 5,333

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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