Investment Securities (Schedule Of Securities Classified As Current And Long-Term) (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Amortized cost	$ 9,113,006	$ 8,175,981
Gross unrealized gains	483,397	258,465
Gross Unrealized Losses	(35,823)	(62,007)
Fair Value	9,560,580	8,372,439
Debt Securities [Member] \| U.S. Treasury And Other U.S. Government Corporations And Agencies [Member] \| U.S. Treasury And Agency Obligations [Member]
Amortized cost	859,543	697,816
Gross unrealized gains	21,656	14,412
Gross Unrealized Losses	(480)	(615)
Fair Value	880,719	711,613
Debt Securities [Member] \| U.S. Treasury And Other U.S. Government Corporations And Agencies [Member] \| Mortgage-Backed Securities [Member]
Amortized cost	1,711,452	1,614,569
Gross unrealized gains	91,379	49,783
Gross Unrealized Losses	(1,179)	(1,173)
Fair Value	1,801,652	1,663,179
Debt Securities [Member] \| Tax-Exempt Municipal Securities [Member]
Amortized cost	2,617,120	2,439,659
Gross unrealized gains	112,228	37,294
Gross Unrealized Losses	(3,659)	(43,619)
Fair Value	2,725,689	2,433,334
Debt Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Amortized cost	48,557	58,017
Gross unrealized gains	512	545
Gross Unrealized Losses	(1,641)	(2,675)
Fair Value	47,428	55,887
Debt Securities [Member] \| Commercial Mortgage-Backed Securities [Member]
Amortized cost	371,278	306,291
Gross unrealized gains	17,798	14,911
Gross Unrealized Losses	(1,165)	(171)
Fair Value	387,911	321,031
Debt Securities [Member] \| Asset-Backed Securities [Member]
Amortized cost	106,186	148,068
Gross unrealized gains	1,397	1,727
Gross Unrealized Losses	(130)	(44)
Fair Value	107,453	149,751
Debt Securities [Member] \| Corporate Debt Securities [Member]
Amortized cost	3,393,537	2,906,228
Gross unrealized gains	238,427	139,793
Gross Unrealized Losses	(27,569)	(13,710)
Fair Value	3,604,395	3,032,311
Debt Securities [Member] \| Redeemable Preferred Stock [Member]
Amortized cost	5,333	5,333
Gross unrealized gains	0	0
Gross Unrealized Losses	0	0
Fair Value	$ 5,333	$ 5,333

- Definition

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.

+ References+ Details