Investment Securities (Summary Of Net Gain From Sale Of Agency Securities) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Cost of Sale of Fair Value Option Securities	$ (3,405,000)	$ (5,218,000)
Cost of Sale of Investment Securities	(3,405,000)	(5,218,000)
Proceeds from Sale of Debt Securities	3,160,000	5,127,000
Proceeds from Sale of Debt Securities, Trading	3,160,000	5,127,000
Proceeds from Sale of Debt Securities, Available-for-sale	0	0
Net gain (loss) on sale of investment securities	(245,000)	(91,000)
Principal Payments Received on Available-For-Sale securities	134,000	143,000
Trading Securities [Member]
Trading Securities Par	67,817,000		$ 63,984,000
Available-for-sale Securities [Member]
Agency MBS sold, at cost	0	0
Net gain (loss) on sale of investment securities		0
Debt Securities, Available-for-sale, Realized Gain	0	0
Debt Securities, Available-for-sale, Realized Loss	0	0
Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities		(91,000)
Debt Securities, Available-for-sale, Realized Gain	21,000	10,000
Debt Securities, Available-for-sale, Realized Loss	266,000	101,000
Securities (Assets) [Member]
Net gain (loss) on sale of investment securities	(245,000)	(91,000)
Debt Securities, Available-for-sale, Realized Gain	21,000	10,000
Debt Securities, Available-for-sale, Realized Loss	266,000	$ 101,000
Cost and Proceeds of Investment Securities [Member] \| Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities	0
Cost and Proceeds of Investment Securities [Member] \| Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities	(245,000)
Gross Gain & Loss of Investment Securities [Member] \| Available-for-sale Securities [Member]
Net gain (loss) on sale of investment securities	0
Gross Gain & Loss of Investment Securities [Member] \| Securities Remeasured at Fair Value [Member]
Net gain (loss) on sale of investment securities	(245,000)
Non-Agency [Member] \| Interest-Only-Strip \| Trading Securities [Member]
Trading Securities Par	93,000		93,000
Agency Securities [Member] \| Interest-Only-Strip \| Trading Securities [Member]
Trading Securities Par	$ 1,975,000		$ 307,000

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