Borrowings (Schedule Of Company's Borrowings) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010
Borrowings [Abstract]
Outstanding borrowings	$ 7,880,814	$ 3,443,843
Interest accrued thereon	3,747	1,084
Weighted average borrowing rate	0.36%	0.32%
Weighted average remaining maturity (in days)	27.6	39.3
Fair value of the collateral	$ 8,284,423	$ 3,657,185
Number of repurchase agreements exceeding 10% of net assets	0	0
Risk percentage	10.00%	0.10%

The carrying value as of the balance sheet date of securities that an institution sells and agrees to repurchase (the identical or substantially the same securities) as a seller-borrower at a specified date for a specified price, also known as a repurchase agreement, or repo. Most repos involve obligations of the federal government or its agencies, but other financial instruments, such as commercial paper, banker's acceptances, and negotiable certificates of deposit, are sometimes used in repos.

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Fair value of financial instrument held by the entity for its own account (proprietary securities) for trading or investment purposes that are carried at fair value and pledged to counterparties as collateral for financing transactions.

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