Capital (Mandatorily Redeemable Capital Stock) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Mandatorily Redeemable Capital Stock [Roll Forward]
Balance at beginning period	$ 210,828
Capital stock subject to mandatory redemption reclassified from equity: Withdrawals	14,618
Capital stock subject to mandatory redemption reclassified from equity: Other redemptions	3,607
Redemption, or other reduction, of mandatorily redeemable capital stock: Withdrawals	(95,098)
Balance at end of period	$ 133,955

The amount that would be paid, determined under the conditions specified in the contract, if as of the reporting date, the holder of the share has the right to redeem the shares.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6940734&loc=d3e22047-110879

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 150

-Paragraph 27

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant