Investment Securities (Details 5)	Jun. 30, 2012	Dec. 31, 2011
Prime Minimum [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	3.00%	4.00%
Lifetime probability of default rates	1.00%	2.00%
Lifetime loss severity rates	32.00%	40.00%
Prime Maximum [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	18.00%	15.00%
Lifetime probability of default rates	8.00%	9.00%
Lifetime loss severity rates	55.00%	50.00%
Prime Average [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	13.00%	14.00%
Lifetime probability of default rates	3.00%	3.00%
Lifetime loss severity rates	39.00%	46.00%
Non-prime Minimum [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	2.00%	2.00%
Lifetime probability of default rates	2.00%	1.00%
Lifetime loss severity rates	45.00%	8.00%
Non-prime Maximum [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	10.00%	11.00%
Lifetime probability of default rates	20.00%	20.00%
Lifetime loss severity rates	88.00%	70.00%
Non-prime Average [Member]
Summary of ranges used in valuation of non-agency mortgage-backed securities other-than-temporarily impaired
Estimated lifetime prepayment rates	7.00%	6.00%
Lifetime probability of default rates	5.00%	5.00%
Lifetime loss severity rates	54.00%	52.00%