Fair Value Disclosures Fair Value Impact on Financial Performance (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Expense	$ (141,656)	$ (165,326)
Net losses on instruments held under the fair value option	532	2,621
Portion at Fair Value, Fair Value Disclosure [Member] | Consolidated Obligation Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest Expense	(1,359)	(2,891)
Net losses on instruments held under the fair value option	532	2,621
Total changes in fair value included in current period earnings	$ (827)	$ (270)