Investment Securities (Narrative) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Principal Investment Gains (Losses)	$ 112,000	$ 133,000	$ 170,000	$ 219,000
Top five states geographic concentration			The top five states geographic concentration comprised in the deal were California 18.2 percent, Arizona 10.5 percent, Virginia 6.1 percent, Florida 6.5 percent and Nevada 6.3 percent. No one state exceeded a 25 percent concentration.
ALESCO Preferred Funding VI [Member]
Excess subordination as a percentage of remainging performing collateral			(47.60%)
ALESCO Preferred Funding VII [Member]
Excess subordination as a percentage of remainging performing collateral			(49.50%)