Investment in Securities (Proceeds, Realized Gains (Losses) on Sales) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Securities, Available-for-sale [Line Items]
Available-for-sale securities Realizes Losses - adjustments to cost basis of certain securities	$ (2,700,000)	$ (1,000,000.0)	$ (8,400,000)	$ 2,500,000
Agency RMBS
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	182,522,000	174,796,000	388,026,000	566,721,000
Debt Securities, Available-for-Sale, Realized Gain	65,000	26,000	852,000	1,207,000
Debt Securities, Available-for-Sale, Realized Loss	(14,517,000)	(21,549,000)	(40,844,000)	(34,027,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	(14,452,000)	(21,523,000)	(39,992,000)	(32,820,000)
Non-Agency RMBS and CMBS
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	14,042,000	1,086,000	41,230,000	7,594,000
Debt Securities, Available-for-Sale, Realized Gain	1,345,000	2,395,000	2,429,000	4,336,000
Debt Securities, Available-for-Sale, Realized Loss	(50,000)	(3,000)	(65,000)	(26,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	1,295,000	2,392,000	2,364,000	4,310,000
CLOs
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	0	2,835,000	0	17,267,000
Debt Securities, Available-for-Sale, Realized Gain	354,000	2,358,000	442,000	4,260,000
Debt Securities, Available-for-Sale, Realized Loss	0	(70,000)	0	(690,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	354,000	2,288,000	442,000	3,570,000
Other Securities
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	436,139,000	79,896,000	710,195,000	93,927,000
Debt Securities, Available-for-Sale, Realized Gain	1,843,000	197,000	2,163,000	3,665,000
Debt Securities, Available-for-Sale, Realized Loss	(1,777,000)	(144,000)	(3,526,000)	(454,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	66,000	53,000	(1,363,000)	3,211,000
Securities Investment [Member]
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	632,703,000	258,613,000	1,139,451,000	685,509,000
Debt Securities, Available-for-Sale, Realized Gain	3,607,000	4,976,000	5,886,000	13,468,000
Debt Securities, Available-for-Sale, Realized Loss	(16,344,000)	(21,766,000)	(44,435,000)	(35,197,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	$ (12,737,000)	$ (16,790,000)	$ (38,549,000)	$ (21,729,000)