Summary Of Significant Accounting Policies (Activity In Redeemable Capital Shares) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary Of Significant Accounting Policies [Abstract]
Redeemable capital shares, prescribed aggregation	50,000
Beginning balance, Shares	386,950,000	260,000,000	218,000,000
Shares issued, Shares	239,050,000	138,950,000	63,500,000
Shares redeemed, Shares	(62,150,000)	(12,000,000)	(21,500,000)
Ending balance, Shares	563,850,000	386,950,000	260,000,000
Beginning balance, value	$ 5,315,950	$ 2,792,233	$ 1,896,305
Shares issued, value	3,660,287	1,748,964	625,072
Shares redeemed, value	(915,939)	(128,153)	(219,965)
Redemption value adjustment, value	356,503	902,906	490,821
Ending balance, value	$ 8,416,801	$ 5,315,950	$ 2,792,233

The aggregate amount to be paid by the entity upon redemption of the security that is classified as temporary equity. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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The number of securities classified as temporary equity that have been issued and are held by the entity's shareholders. Securities outstanding equals securities issued minus securities held in treasury. Temporary equity is a security with redemption features that are outside the control of the issuer, is not classified as an asset or liability in conformity with GAAP, and is not mandatorily redeemable. Includes any type of security that is redeemable at a fixed or determinable price or on a fixed or determinable date or dates, is redeemable at the option of the holder, or has conditions for redemption which are not solely within the control of the issuer. If convertible, the issuer does not control the actions or events necessary to issue the maximum number of shares that could be required to be delivered under the conversion option if the holder exercises the option to convert the stock to another class of equity. If the security is a warrant or a rights issue, the warrant or rights issue is considered to be temporary equity if the issuer cannot demonstrate that it would be able to deliver upon the exercise of the option by the holder in all cases. Includes stock with put option held by ESOP and stock redeemable by holder only in the event of a change in control of the issuer.

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