Stockholders' Equity (Details 3) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Amounts Reclassified from AOCI
Gain on sales of MBS and U.S. Treasury securities, net	$ 1,633,000	$ 2,953,000
Accumulated Other Comprehensive Income/(Loss)
Other-than-temporary impairments recognized in accumulated other comprehensive(loss)/income	979,000		2,600,000
Available-for-sale MBS and U.S. Treasury securities
Amounts Reclassified from AOCI
Total reclassifications for period	(1,360,000)
Available-for-sale MBS and U.S. Treasury securities | Amounts Reclassified from AOCI
Amounts Reclassified from AOCI
Gain on sales of MBS and U.S. Treasury securities, net	(1,360,000)
Total reclassifications for period	$ (1,360,000)