Fair Value of Financial Instruments Level 3 (Details) (Fair Value, Measurements, Recurring [Member], Fair Value, Inputs, Level 3 [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	$ 105,245
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	26,021
Unrealized (loss) gain included in OCI	(4,157)
Principal payments	14,354
Amortization	42
Balance at the end of the period	112,797
Non-Agency CMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	100,102
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	26,021
Unrealized (loss) gain included in OCI	(4,089)
Principal payments	12,440
Amortization	20
Balance at the end of the period	109,614
Non-Agency RMBS [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	5,118
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0
Unrealized (loss) gain included in OCI	(68)
Principal payments	1,914
Amortization	22
Balance at the end of the period	3,158
Other Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at the beginning of the period	25
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases
Unrealized (loss) gain included in OCI
Principal payments
Amortization
Balance at the end of the period	$ 25