Investment Securities (Components Of Investment Securities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 34,977,000	$ 45,262,000
Debt Securities, Trading and Available-for-sale	$ 40,904,000	$ 54,421,000
Weighted average coupon	3.94%	3.08%
Weighted average yield	3.37%	2.43%
Future Prepayment Rate Assumption Of Investment Portfolio	7.40%	10.90%
Fannie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 22,731,000	$ 29,198,000
Debt Securities, Trading and Available-for-sale	$ 27,201,000	$ 36,073,000
Weighted average coupon	3.79%	3.09%
Weighted average yield	3.17%	2.38%
Freddie Mac [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 10,830,000	$ 14,244,000
Debt Securities, Trading and Available-for-sale	$ 12,286,000	$ 16,526,000
Weighted average coupon	3.92%	2.98%
Weighted average yield	3.41%	2.29%
Ginnie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 2,000	$ 3,000
Debt Securities, Trading and Available-for-sale	$ 3,000	$ 5,000
Weighted average coupon	4.66%	4.69%
Weighted average yield	2.58%	2.54%
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 90,000	$ 329,000
Debt Securities, Trading and Available-for-sale	$ 90,000	$ 329,000
Weighted average coupon	4.52%	3.33%
Weighted average yield	4.34%	5.68%
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 567,000	$ 514,000
Debt Securities, Trading and Available-for-sale	$ 567,000	$ 514,000
Weighted average coupon	6.06%	3.60%
Weighted average yield	6.02%	4.28%
Credit Risk Transfer Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading	$ 757,000	$ 974,000
Debt Securities, Trading and Available-for-sale	$ 757,000
Weighted average coupon	8.48%	3.74%
Weighted average yield	7.93%	4.47%
Available-for-sale Securities [Member]
Schedule of Investments [Line Items]
Par value	$ 6,232,000	$ 8,458,000
Debt Securities, Available-for-Sale, Unamortized discount	1,000	4,000
Debt Securities, Available-for-Sale, Unamortized premium	368,000	404,000
Debt Securities, Available-for-sale, Amortized Cost	6,599,000	8,858,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	672,000	0
Total available-for-sale securities, at fair value	5,927,000	9,159,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	0	301,000
Available-for-sale Securities [Member] | Fannie Mae [Member]
Schedule of Investments [Line Items]
Par value	4,696,000	6,345,000
Debt Securities, Available-for-Sale, Unamortized discount	1,000	3,000
Debt Securities, Available-for-Sale, Unamortized premium	275,000	299,000
Debt Securities, Available-for-sale, Amortized Cost	4,970,000	6,641,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	500,000	0
Total available-for-sale securities, at fair value	4,470,000	6,875,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	0	234,000
Available-for-sale Securities [Member] | Freddie Mac [Member]
Schedule of Investments [Line Items]
Par value	1,535,000	2,111,000
Debt Securities, Available-for-Sale, Unamortized discount	0	1,000
Debt Securities, Available-for-Sale, Unamortized premium	93,000	105,000
Debt Securities, Available-for-sale, Amortized Cost	1,628,000	2,215,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	172,000	0
Total available-for-sale securities, at fair value	1,456,000	2,282,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	0	67,000
Available-for-sale Securities [Member] | Ginnie Mae [Member]
Schedule of Investments [Line Items]
Par value	1,000	2,000
Debt Securities, Available-for-Sale, Unamortized discount	0	0
Debt Securities, Available-for-Sale, Unamortized premium	0	0
Debt Securities, Available-for-sale, Amortized Cost	1,000	2,000
Debt Securities, Available-for-Sale, Gross Unrealized Losses	0	0
Total available-for-sale securities, at fair value	1,000	2,000
Debt Securities, Available-for-Sale, Gross Unrealized Gains	0	0
Trading Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	29,000	768,000
Debt Securities, Trading Securities, Gross Unrealized Losses	3,333,000	276,000
Trading Securities Par	37,171,000	43,420,000
Debt Securities, Trading Securities, Unamortized discount	116,000	37,000
Debt Securities, Trading Securities, Unamortized Premium	1,226,000	1,387,000
Debt Securities, Trading, Amortized Cost	38,281,000	44,770,000
Trading Securities [Member] | Fannie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	13,000	517,000
Debt Securities, Trading Securities, Gross Unrealized Losses	2,307,000	181,000
Trading Securities Par	24,231,000	27,952,000
Debt Securities, Trading Securities, Unamortized discount	61,000	14,000
Debt Securities, Trading Securities, Unamortized Premium	855,000	924,000
Debt Securities, Trading, Amortized Cost	25,025,000	28,862,000
Trading Securities [Member] | Freddie Mac [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	8,000	213,000
Debt Securities, Trading Securities, Gross Unrealized Losses	937,000	89,000
Trading Securities Par	11,444,000	13,680,000
Debt Securities, Trading Securities, Unamortized discount	37,000	4,000
Debt Securities, Trading Securities, Unamortized Premium	352,000	444,000
Debt Securities, Trading, Amortized Cost	11,759,000	14,120,000
Trading Securities [Member] | Ginnie Mae [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	0	0
Debt Securities, Trading Securities, Gross Unrealized Losses	0	0
Trading Securities Par	2,000	3,000
Debt Securities, Trading Securities, Unamortized discount	0	0
Debt Securities, Trading Securities, Unamortized Premium	0	0
Debt Securities, Trading, Amortized Cost	2,000	3,000
Trading Securities [Member] | Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	0	6,000
Debt Securities, Trading Securities, Gross Unrealized Losses	21,000	2,000
Trading Securities Par	112,000	327,000
Debt Securities, Trading Securities, Unamortized discount	4,000	6,000
Debt Securities, Trading Securities, Unamortized Premium	3,000	4,000
Debt Securities, Trading, Amortized Cost	111,000	325,000
Trading Securities [Member] | Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	0	11,000
Debt Securities, Trading Securities, Gross Unrealized Losses	38,000	2,000
Trading Securities Par	609,000	508,000
Debt Securities, Trading Securities, Unamortized discount	8,000	6,000
Debt Securities, Trading Securities, Unamortized Premium	4,000	3,000
Debt Securities, Trading, Amortized Cost	605,000	505,000
Trading Securities [Member] | Credit Risk Transfer Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading Securities, Gross Unrealized Gains	8,000	21,000
Debt Securities, Trading Securities, Gross Unrealized Losses	30,000	2,000
Trading Securities Par	773,000	950,000
Debt Securities, Trading Securities, Unamortized discount	6,000	7,000
Debt Securities, Trading Securities, Unamortized Premium	12,000	12,000
Debt Securities, Trading, Amortized Cost	779,000	955,000
Securities Remeasured at Fair Value [Member] | Credit Risk Transfer Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale		974,000
Mortgage-backed Securities, Issued by Private Enterprises [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale	90,000	329,000
Commercial Mortgage Backed Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale	567,000	514,000
Credit Risk Transfer Securities [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale	757,000	974,000
Credit Risk Transfer Securities [Member] | Securities Remeasured at Fair Value [Member]
Schedule of Investments [Line Items]
Debt Securities, Trading and Available-for-sale	$ 757,000	$ 974,000