Borrowings (Details 2) (USD $)			3 Months Ended		3 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Reverse repurchase agreements	Dec. 31, 2012 Reverse repurchase agreements	Jun. 30, 2013 FHLB-NY advances FHLB-NY	Dec. 31, 2012 FHLB-NY advances FHLB-NY	Jun. 30, 2013 Restructured Borrowings	Jun. 30, 2013 Restructured Borrowings
Borrowings
Weighted Average Rate (as a percent)	2.64%	3.03%	4.08%	4.32%	2.01%	2.07%	3.54%	3.54%
Callable borrowings	$ 1,950,000,000	$ 1,950,000,000
Borrowings restructured with the counterparties			300,000,000		850,000,000		1,150,000,000
Weighted average rate before restructuring of borrowings (as a percent)							4.44%	4.44%
Weighted average remaining term before restructuring of borrowings								4 years
Weighted average remaining term								7 years
Restructured borrowings of which contractual call dates extended to 2017								950,000,000
Restructured borrowings of which contractual call dates extended to 2016								$ 100,000,000