Investment in Securities (Proceeds, Realized Gains (Losses) on Sales) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Securities, Available-for-sale [Line Items]
Available-for-sale securities Realizes Losses - adjustments to cost basis of certain securities	$ (31,700,000)	$ (6,000,000.0)	$ (3,300,000)
Agency RMBS
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	1,394,118,000	1,090,180,000	963,052,000
Debt Securities, Available-for-Sale, Realized Gain	1,142,000	2,159,000	5,389,000
Debt Securities, Available-for-Sale, Realized Loss	(57,677,000)	(100,959,000)	(10,859,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	(56,535,000)	(98,800,000)	(5,470,000)
Non-Agency RMBS and CMBS
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	131,697,000	30,171,000	207,232,000
Debt Securities, Available-for-Sale, Realized Gain	2,993,000	6,907,000	14,144,000
Debt Securities, Available-for-Sale, Realized Loss	(1,297,000)	(2,707,000)	(2,723,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	1,696,000	4,200,000	11,421,000
CLOs
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	210,000	18,259,000	130,747,000
Debt Securities, Available-for-Sale, Realized Gain	1,547,000	7,597,000	4,163,000
Debt Securities, Available-for-Sale, Realized Loss	(171,000)	(747,000)	(976,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	1,376,000	6,850,000	3,187,000
Other Securities
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	1,278,153,000	326,008,000	194,025,000
Debt Securities, Available-for-Sale, Realized Gain	6,898,000	4,294,000	2,588,000
Debt Securities, Available-for-Sale, Realized Loss	(7,298,000)	(1,661,000)	(927,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	(400,000)	2,633,000	1,661,000
Securities Investment [Member]
Securities, Available-for-sale [Line Items]
Proceeds from Sale and Maturity of Debt Securities, Available-for-Sale	2,804,178,000	1,464,618,000	1,495,056,000
Debt Securities, Available-for-Sale, Realized Gain	12,580,000	20,957,000	26,284,000
Debt Securities, Available-for-Sale, Realized Loss	(66,443,000)	(106,074,000)	(15,485,000)
Debt Securities, Available-for-Sale, Realized Gain (Loss)	$ (53,863,000)	$ (85,117,000)	$ 10,799,000