Derivative Instruments (Schedule of Information Related to Derivative Instruments) (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Derivative [Line Items]
Notional amount	$ 287,725,000	$ 32,600,000
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional amount	225,725,000	32,600,000
TBAs [Member]
Derivative [Line Items]
Notional amount	$ 62,000,000