Borrowed Funds (Details 2) (USD $) In Thousands, unless otherwise specified			6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2011 2011 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2011 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2012 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2012 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2013 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2013 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2014 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2014 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2015 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2015 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2016 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2016 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2017 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2017 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2018 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2018 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2019 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2019 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 2020 [Member] Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 2020 [Member] Borrowings by earlier of scheduled maturity or next potential put date [Member]	Jun. 30, 2011 Borrowings by Scheduled Maturity Date [Member]	Jun. 30, 2011 Borrowings by earlier of scheduled maturity or next potential put date [Member]
Borrowed funds maturities and potential put dates
Borrowed funds	$ 21,125,000	$ 29,675,000	$ 1,650,000	$ 8,025,000	$ 2,900,000	$ 3,600,000	$ 100,000	$ 1,325,000	$ 0	$ 3,725,000	$ 225,000	$ 275,000	$ 4,525,000	$ 3,925,000	$ 5,875,000	$ 0	$ 850,000	$ 250,000	$ 1,725,000	$ 0	$ 3,275,000	$ 0	$ 21,125,000	$ 21,125,000
Weighted Average Rate			0.76%	3.56%	0.88%	1.57%	5.46%	4.69%	0.00%	4.47%	4.23%	4.10%	4.82%	4.92%	4.30%	0.00%	3.62%	3.10%	4.62%	0.00%	4.53%	0.00%	3.71%	3.71%