Repurchase Arrangements And Similar Borrowings, Including Related Hedging Activity (Narrative) (Details)	6 Months Ended
Jun. 30, 2011
Swap agreements average expiration period	15 months
Percentage of Haircuts on pledged agency securities	4.60
Maximum [Member]
Maturity period of repurchase arrangements (days)	90
Minimum [Member]
Maturity period of repurchase arrangements (days)	30

This describes the time frame of the terms of the entity's repurchase agreements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(m)(1)(i)(A))
-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Name:	us-gaap_RepurchaseAgreementsMaturities
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration