Counterparty Risk (% Of Total Collateral On Reverse Repurchase Agreements) (Details)	Dec. 31, 2012
Deutsche Bank [Member]
Financial Highlights [Line Items]
% of Total Collateral on Reverse Repurchase Agreements	32.00%
Royal Bank Of Canada [Member]
Financial Highlights [Line Items]
% of Total Collateral on Reverse Repurchase Agreements	28.00%