Consolidated Condensed Schedule Of Investments (Long Investments) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2012		Dec. 31, 2011
Schedule of Investments [Line Items]
Fair Value	$ 1,131,242		$ 1,212,483
Investments at value, cost	1,126,541		1,234,203
U.S. Treasury Securities [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	1.27%		2.72%
Unrated But Agency-Guaranteed [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	179.14%		206.07%
Long Investment AAA Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	0.33%		1.25%
Long Investment AA Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	0.57%		1.88%
Long Investment A Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	2.39%		5.44%
Long Investment BBB Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	2.82%		3.46%
Long Investment BB Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	98.49%		103.36%
Long Investment Unrated Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	1.18%		2.71%
Long Investments [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	286.19%	[1],[2]	326.89%	[1],[3]
Fair Value	1,131,242	[1],[2]	1,212,483	[1],[3]
Investments at value, cost	1,126,541	[1],[2]	1,234,203	[1],[3]
Long Investments [Member] | Federal Home Loan Mortgage Corporation [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	31.99%		63.62%
Long Investments [Member] | Government National Mortgage Association [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.10%		0.41%
Long Investments [Member] | Federal National Mortgage Association [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	147.05%		142.04%
Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	283.74%	[1],[2]	322.98%	[1],[3]
Fair Value	1,121,547	[1],[2]	1,197,970	[1],[3]
Investments at value, cost	1,116,653	[1],[2]	1,219,423	[1],[3]
Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	179.14%	[1],[2],[4]	206.07%	[1],[3],[5]
Fair Value	708,083	[1],[2],[4]	764,344	[1],[3],[5]
Investments at value, cost	699,582	[1],[2],[4]	755,771	[1],[3],[5]
Fixed Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	173.35%	[1],[2],[4]	195.78%	[1],[3],[5]
Fair Value	685,193	[1],[2],[4]	726,160	[1],[3],[5]
Investments at value, cost	677,235	[1],[2],[4]	718,177	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	157.60%	[1],[2],[4]	185.76%	[1],[3],[5]
Fair Value	622,967	[1],[2],[4]	689,018	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 148,357 Federal National Mortgage Association Pool 4.00% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	148,357	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	158,145	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 85,000 Federal Home Loan Mortgage Corporation Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			85,000	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			90,611	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 25,882 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			25,882	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-07	[1],[3],[5]
Fair Value			28,107	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2040-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			25,456	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2040-11	[1],[3],[5]
Fair Value			26,824	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			24,164	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-12	[1],[3],[5]
Fair Value			25,874	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 20,212 Federal National Mortgage Association Pool 5.00% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			20,212	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-08	[1],[3],[5]
Fair Value			21,937	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 18,434 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			18,434	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			19,738	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 17,182 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			17,182	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			18,328	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 5.00% 2039-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			15,465	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2039-09	[1],[3],[5]
Fair Value			16,620	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 15,243 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			15,243	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			16,260	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 14,964 Federal National Mortgage Association Pool 4.50% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			14,964	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-11	[1],[3],[5]
Fair Value			15,991	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 13,451 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			13,451	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			14,348	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 13,033 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			13,033	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			13,927	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 13,125 Federal National Mortgage Association Pool 4.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			13,125	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			13,818	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 12,593 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			12,593	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-07	[1],[3],[5]
Fair Value			13,699	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 11,095 Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			11,095	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			12,098	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 10,358 Federal Home Loan Mortgage Corporation Pool 4.00% 2041-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			10,358	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-01	[1],[3],[5]
Fair Value			10,902	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 9,149 Federal Home Loan Mortgage Corporation Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			9,149	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			9,736	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 9,027 Federal National Mortgage Association Pool 4.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			9,027	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			9,498	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2041-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			8,400	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-03	[1],[3],[5]
Fair Value			8,851	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 8,123 Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			8,123	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			8,836	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 7,437 Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			7,437	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			8,072	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2026-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			9,152	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2026-05	[1],[3],[5]
Fair Value			9,657	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 5.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			9,995	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			10,791	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			18,120	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			19,397	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	22,541	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	24,028	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 23,379 Federal National Mortgage Association Pool 4.50% 2041-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	23,379	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-12	[1],[2],[4]
Fair Value	25,236	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 19,656 Federal National Mortgage Association Pool 4.00% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	19,656	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	20,996	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 18,957 Federal National Mortgage Association Pool 5.00% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,957	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-08	[1],[2],[4]
Fair Value	20,637	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,218	[1],[2],[4]	18,867	[1],[3],[5]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]	Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate	5.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2041-07	[1],[2],[4]	2041-07	[1],[3],[5]
Fair Value	19,744	[1],[2],[4]	20,417	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	16,056	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-09	[1],[2],[4]
Fair Value	17,286	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 18,002 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,002	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-09	[1],[2],[4]
Fair Value	19,471	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 17,715 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	17,715	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	19,116	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	16,696	[1],[2],[4]	17,391	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2041-03	[1],[2],[4]	2041-03	[1],[3],[5]
Fair Value	18,254	[1],[2],[4]	18,941	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 13,266 Federal National Mortgage Association Pool 4.00% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	13,266	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	14,154	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	12,974	[1],[2],[4]	13,554	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	4.00%	[1],[2],[4]	4.00%	[1],[3],[5]
Maturity	2041-11	[1],[2],[4]	2041-11	[1],[3],[5]
Fair Value	13,842	[1],[2],[4]	14,252	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 12,822 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	12,822	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-09	[1],[2],[4]
Fair Value	13,804	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 11,711 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	11,711	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-07	[1],[2],[4]
Fair Value	12,777	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,667	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-09	[1],[2],[4]
Fair Value	5,102	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 11,016 Federal National Mortgage Association Pool 4.00% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	11,016	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	11,743	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 10,689 Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	10,689	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-09	[1],[2],[4]
Fair Value	11,686	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2026-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	10,510	[1],[2],[4]	11,361	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	4.50%	[1],[2],[4]	4.50%	[1],[3],[5]
Maturity	2026-04	[1],[2],[4]	2026-04	[1],[3],[5]
Fair Value	11,305	[1],[2],[4]	12,154	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.50% 2041-02 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	9,093	[1],[2],[4]	9,176	[1],[3],[5]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]	Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate	4.50%	[1],[2],[4]	4.50%	[1],[3],[5]
Maturity	2041-02	[1],[2],[4]	2041-02	[1],[3],[5]
Fair Value	9,803	[1],[2],[4]	9,805	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	9,077	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	9,746	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2026-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	8,670	[1],[2],[4]	9,468	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	4.00%	[1],[2],[4]	4.00%	[1],[3],[5]
Maturity	2026-07	[1],[2],[4]	2026-07	[1],[3],[5]
Fair Value	9,243	[1],[2],[4]	10,011	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.50% 2039-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	8,084	[1],[2],[4]	8,468	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2039-10	[1],[2],[4]	2039-10	[1],[3],[5]
Fair Value	8,864	[1],[2],[4]	9,269	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,602	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-06	[1],[2],[4]
Fair Value	7,187	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.50% 2040-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,395	[1],[2],[4]	7,261	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2040-05	[1],[2],[4]	2040-05	[1],[3],[5]
Fair Value	7,011	[1],[2],[4]	7,947	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 6,955 Federal National Mortgage Association Pool 5.00% 2041-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,955	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-06	[1],[3],[5]
Fair Value			7,553	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 6,878 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,878	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-07	[1],[3],[5]
Fair Value			7,465	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,852	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-05	[1],[3],[5]
Fair Value			7,437	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 6,823 Federal National Mortgage Association Pool 5.00% 2041-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,823	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-06	[1],[3],[5]
Fair Value			7,406	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,836 Federal National Mortgage Association Pool 5.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			5,836	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			6,334	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,687 Federal National Mortgage Association Pool 4.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			5,687	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			5,987	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,711 Federal National Mortgage Association Pool 3.50% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			5,711	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			3.50%	[1],[3],[5]
Maturity			2041-11	[1],[3],[5]
Fair Value			5,883	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2041-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			5,549	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-05	[1],[3],[5]
Fair Value			5,833	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,888 Federal National Mortgage Association Pool 5.00% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,888	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-08	[1],[3],[5]
Fair Value			5,330	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,837	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-04	[1],[3],[5]
Fair Value			5,190	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,702 Federal National Mortgage Association Pool 5.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,702	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			5,127	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,398	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			3.50%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			4,522	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,150 Federal National Mortgage Association Pool 5.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,150	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-10	[1],[3],[5]
Fair Value			4,504	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,230 Federal National Mortgage Association Pool 4.00% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,230	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-09	[1],[3],[5]
Fair Value			4,454	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,158 Federal Home Loan Mortgage Corporation Pool 4.00% 2041-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,158	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2041-01	[1],[3],[5]
Fair Value			4,384	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,100 Federal National Mortgage Association Pool 4.50% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			4,100	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			4.50%	[1],[3],[5]
Maturity			2041-11	[1],[3],[5]
Fair Value			4,374	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,751 Federal National Mortgage Association Pool 3.50% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			3,751	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			3.50%	[1],[3],[5]
Maturity			2041-11	[1],[3],[5]
Fair Value			3,859	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,565 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			2,565	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-07	[1],[3],[5]
Fair Value			2,791	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,391 Federal National Mortgage Association Pool 5.00% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			2,391	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.00%	[1],[3],[5]
Maturity			2041-11	[1],[3],[5]
Fair Value			2,595	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation Pool 6.00% 2040-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			1,197	[1],[3],[5]
Description			Other Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			6.00%	[1],[3],[5]
Maturity			2040-05	[1],[3],[5]
Fair Value			1,319	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Government National Mortgage Association Pool 5.50% 2041-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			806	[1],[3],[5]
Description			Other Government National Mortgage Association Pool	[1],[3],[5]
Rate			5.50%	[1],[3],[5]
Maturity			2041-03	[1],[3],[5]
Fair Value			907	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 6,263 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,263	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-07	[1],[2],[4]
Fair Value	6,779	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2039-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,083	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2039-11	[1],[2],[4]
Fair Value	6,584	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2042-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,012	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-05	[1],[2],[4]
Fair Value	6,440	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,639	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	6,023	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,523	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	6,005	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2026-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,398	[1],[2],[4]	6,759	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	4.00%	[1],[2],[4]	4.00%	[1],[3],[5]
Maturity	2026-06	[1],[2],[4]	2026-06	[1],[3],[5]
Fair Value	5,755	[1],[2],[4]	7,147	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 6.00% 2039-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,083	[1],[2],[4]	5,531	[1],[3],[5]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]	Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate	6.00%	[1],[2],[4]	6.00%	[1],[3],[5]
Maturity	2039-04	[1],[2],[4]	2039-04	[1],[3],[5]
Fair Value	5,594	[1],[2],[4]	6,095	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2040-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,092	[1],[2],[4]	5,514	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2040-11	[1],[2],[4]	2040-11	[1],[3],[5]
Fair Value	5,543	[1],[2],[4]	5,985	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,132 Federal National Mortgage Association Pool 4.00% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,132	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	5,517	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,984	[1],[2],[4]	5,209	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	4.50%	[1],[2],[4]	4.50%	[1],[3],[5]
Maturity	2041-08	[1],[2],[4]	2041-08	[1],[3],[5]
Fair Value	5,365	[1],[2],[4]	5,557	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,064	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	5,332	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,849 Federal National Mortgage Association Pool 5.00% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,849	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-08	[1],[2],[4]
Fair Value	5,301	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,891 Federal National Mortgage Association Pool 4.50% 2041-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,891	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-12	[1],[2],[4]
Fair Value	5,266	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2042-02 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,511	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-02	[1],[2],[4]
Fair Value	4,804	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2040-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,029	[1],[2],[4]	4,799	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2040-06	[1],[2],[4]	2040-06	[1],[3],[5]
Fair Value	4,386	[1],[2],[4]	5,209	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,068	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-11	[1],[2],[4]
Fair Value	4,379	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,854 Federal National Mortgage Association Pool 4.00% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,854	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	4,133	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,793 Federal National Mortgage Association Pool 4.50 % 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,793	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	4,115	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,690	[1],[2],[4]	3,724	[1],[3],[5]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]	Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate	4.50%	[1],[2],[4]	4.50%	[1],[3],[5]
Maturity	2041-09	[1],[2],[4]	2041-09	[1],[3],[5]
Fair Value	3,962	[1],[2],[4]	3,963	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,250 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,250	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	3,510	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2042-02 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,326	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-02	[1],[2],[4]
Fair Value	3,496	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,697 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,697	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2041-10	[1],[2],[4]
Fair Value	2,904	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,530	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	2,656	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,258 Federal National Mortgage Association Pool 4.50% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,258	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.50%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]
Fair Value	2,444	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool (Pre-Issue) 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,234	[1],[2],[4]
Description	Federal National Mortgage Association Pool (Pre-Issue)	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	2,350	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2042-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,203	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-03	[1],[2],[4]
Fair Value	2,320	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 1,966 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	1,966	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2041-07	[1],[2],[4]
Fair Value	2,145	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association Pools [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	8,599	[1],[2],[4]	4,609	[1],[3],[5]
Description	Other Federal National Mortgage Association Pools	[1],[2],[4]	Other Federal National Mortgage Association Pools	[1],[3],[5]
Rate			6.00%	[1],[3],[5]
Fair Value	9,370	[1],[2],[4]	5,092	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association Pools [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	6.00%	[1],[2],[4]
Maturity	2042-04	[1],[2],[4]	2040-02	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association Pools [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	3.50%	[1],[2],[4]
Maturity	2039-09	[1],[2],[4]	2039-09	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation Pool [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	1,189	[1],[2],[4]
Description	Other Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	6.00%	[1],[2],[4]
Maturity	2040-05	[1],[2],[4]
Fair Value	1,309	[1],[2],[4]
Interest Only - Fixed Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	1.14%	[1],[2],[4]	1.38%	[1],[3],[5]
Fair Value	4,487	[1],[2],[4]	5,109	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Government National Mortgage Association 5.50% 2036-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	7,089	[1],[2],[4]	9,281	[1],[3],[5]
Description	Other Government National Mortgage Association	[1],[2],[4]	Other Government National Mortgage Association	[1],[3],[5]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2036-03	[1],[2],[4]	2036-03	[1],[3],[5]
Fair Value	387	[1],[2],[4]	603	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	12,235	[1],[2],[4]	13,937	[1],[3],[5]
Description	Other Federal Home Loan Mortgage Corporation	[1],[2],[4]	Other Federal Home Loan Mortgage Corporation	[1],[3],[5]
Fair Value	1,368	[1],[2],[4]	1,772	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2039-01	[1],[2],[4]	2039-01	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	5.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2033-06	[1],[2],[4]	2033-06	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	27,106	[1],[2],[4]	24,381	[1],[3],[5]
Description	Other Federal National Mortgage Association	[1],[2],[4]	Other Federal National Mortgage Association	[1],[3],[5]
Fair Value	2,732	[1],[2],[4]	2,734	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2040-10	[1],[2],[4]	2040-10	[1],[3],[5]
Interest Only - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	4.00%	[1],[2],[4]	5.00%	[1],[3],[5]
Maturity	2036-01	[1],[2],[4]	2036-01	[1],[3],[5]
TBA - Fixed Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	14.61%	[1],[2],[4]	8.64%	[1],[3],[5]
Fair Value	57,739	[1],[2],[4]	32,033	[1],[3],[5]
TBA - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association (30 Year) 4.00% 2012-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			30,500	[1],[3],[5]
Description			Federal National Mortgage Association (30 Year)	[1],[3],[5]
Rate			4.00%	[1],[3],[5]
Maturity			2012-01	[1],[3],[5]
Fair Value			32,033	[1],[3],[5]
TBA - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4.00% 2012-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	41,350	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation (30 Year)	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2012-07	[1],[2],[4]
Fair Value	43,889	[1],[2],[4]
TBA - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation (30 Year) 3.50% 2012-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	13,000	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation (30 Year)	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2012-07	[1],[2],[4]
Fair Value	13,640	[1],[2],[4]
TBA - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association (30 Year) 3.50% 2012-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	200	[1],[2],[4]
Description	Other Federal National Mortgage Association (30 Year)	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2012-07	[1],[2],[4]
Fair Value	210	[1],[2],[4]
Floating Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	5.79%	[1],[2],[4]	10.29%	[1],[3],[5]
Fair Value	22,890	[1],[2],[4]	38,184	[1],[3],[5]
Investments at value, cost	22,347	[1],[2],[4]	37,594	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	5.74%	[1],[2],[4]	10.23%	[1],[3],[5]
Fair Value	22,710	[1],[2],[4]	37,956	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.10% 2038-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			9,464	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.10%	[1],[3],[5]
Maturity			2038-05	[1],[3],[5]
Fair Value			9,969	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.28% 2035-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,675	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.28%	[1],[3],[5]
Maturity			2035-12	[1],[3],[5]
Fair Value			7,027	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.29% 2038-02 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			6,627	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.29%	[1],[3],[5]
Maturity			2038-02	[1],[3],[5]
Fair Value			6,954	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 2.71% 2034-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			3,364	[1],[3],[5]
Description			Federal Home Loan Mortgage Corporation Pool	[1],[3],[5]
Rate			2.71%	[1],[3],[5]
Maturity			2034-07	[1],[3],[5]
Fair Value			3,524	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.52% 2037-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			3,261	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.52%	[1],[3],[5]
Maturity			2037-07	[1],[3],[5]
Fair Value			3,493	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.44% 2037-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			1,906	[1],[3],[5]
Description			Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.44%	[1],[3],[5]
Maturity			2037-09	[1],[3],[5]
Fair Value			2,023	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Other Federal National Mortgage Association Pool 5.01% 2033-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			1,444	[1],[3],[5]
Description			Other Federal National Mortgage Association Pool	[1],[3],[5]
Rate			5.01%	[1],[3],[5]
Maturity			2033-10	[1],[3],[5]
Fair Value			1,525	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.08% 2038-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	7,949	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.08%	[1],[2],[4]
Maturity	2038-05	[1],[2],[4]
Fair Value	8,382	[1],[2],[4]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.26% 2035-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,916	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.26%	[1],[2],[4]
Maturity	2035-12	[1],[2],[4]
Fair Value	6,236	[1],[2],[4]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.51% 2037-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,222	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.51%	[1],[2],[4]
Maturity	2037-07	[1],[2],[4]
Fair Value	3,454	[1],[2],[4]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.69% 2036-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,038	[1],[2],[4]	3,247	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.69%	[1],[2],[4]	5.69%	[1],[3],[5]
Maturity	2036-04	[1],[2],[4]	2036-04	[1],[3],[5]
Fair Value	3,221	[1],[2],[4]	3,441	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Other Federal National Mortgage Association Pool 5.27% 2037-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	1,333	[1],[2],[4]
Description	Other Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.27%	[1],[2],[4]
Maturity	2037-09	[1],[2],[4]
Fair Value	1,417	[1],[2],[4]
Interest Only - Floating Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.05%	[1],[2],[4]	0.06%	[1],[3],[5]
Fair Value	180	[1],[2],[4]	228	[1],[3],[5]
Interest Only - Floating Rate Agency Securities [Member] | Other Federal National Mortgage Association 5.50% 2036-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	1,265	[1],[2],[4]	1,476	[1],[3],[5]
Description	Other Federal National Mortgage Association	[1],[2],[4]	Other Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.50%	[1],[2],[4]	5.50%	[1],[3],[5]
Maturity	2036-08	[1],[2],[4]	2036-08	[1],[3],[5]
Fair Value	180	[1],[2],[4]	228	[1],[3],[5]
Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	104.60%	[1],[2]	116.91%	[1],[3]
Fair Value	413,464	[1],[2]	433,626	[1],[3]
Investments at value, cost	417,071	[1],[2]	463,652	[1],[3]
Principal And Interest - Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	104.35%	[1],[2]	114.91%	[1],[3]
Fair Value	412,487	[1],[2]	426,202	[1],[3]
Investments at value, cost	416,022	[1],[2]	456,170	[1],[3]
Principal And Interest - Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	721,873	[1],[2]	762,480	[1],[3]
Description	Various	[1],[2]	Various	[1],[3]
Fair Value	412,487	[1],[2]	426,202	[1],[3]
Principal And Interest - Private Label Securities [Member] | Various Issuer [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	9.35%	[1],[2]	9.35%	[1],[3]
Maturity	2051-02	[1],[2]	2047-12	[1],[3]
Principal And Interest - Private Label Securities [Member] | Various Issuer [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	0.31%	[1],[2]	0.35%
Maturity	2019-05	[1],[2]	2019-05	[1],[3]
Interest Only - Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.25%	[1],[2]	0.48%	[1],[3]
Fair Value	977	[1],[2]	1,774	[1],[3]
Investments at value, cost	547	[1],[2]	1,471	[1],[3]
Interest Only - Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	63,380	[1],[2]	76,167	[1],[3]
Description	Various	[1],[2]	Various	[1],[3]
Maturity	2047-09	[1],[2]
Fair Value	977	[1],[2]	1,774	[1],[3]
Interest Only - Private Label Securities [Member] | Various Issuer [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	0.65%	[1],[2]	6.91%	[1],[3]
Maturity			2047-09	[1],[3]
Interest Only - Private Label Securities [Member] | Various Issuer [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	0.50%	[1],[2]	0.50%	[1],[3]
Maturity			2035-07	[1],[3]
Other Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.00%	[1],[2]	1.52%	[1],[3]
Fair Value	0	[1],[2]	5,650	[1],[3]
Investments at value, cost	502	[1],[2]	6,011	[1],[3]
Other Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	185,294	[1],[2]	201,831	[1],[3]
Description	Various	[1],[2]	Various	[1],[3]
Rate	0.00%	[1],[2]	0.00%	[1],[3]
Maturity	2037-06	[1],[2]
Fair Value	0	[1],[2]	5,650	[1],[3]
Other Private Label Securities [Member] | Various Issuer [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Maturity			2046-09	[1],[3]
Other Private Label Securities [Member] | Various Issuer [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Maturity			2037-06	[1],[3]
Commercial Mortgage Loans [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	1.18%	[1],[2],[6]	1.19%	[1],[3],[6]
Fair Value	4,650	[1],[2],[6]	4,400	[1],[3],[6]
Investments at value, cost	4,839	[1],[2],[6]	4,789	[1],[3],[6]
Commercial Mortgage Loans [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,000	[1],[2],[6]	5,000	[1],[3],[6]
Description	Various	[1],[2],[6]	Various	[1],[3],[6]
Rate	6.25%	[1],[2],[6]	6.25%	[1],[3],[6]
Maturity	2012-11	[1],[2],[6]	2012-11	[1],[3],[6]
Fair Value	4,650	[1],[2],[6]	4,400	[1],[3],[6]
U.S. Treasury Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	1.27%	[1],[2]	2.72%	[1],[3]
Fair Value	5,045	[1],[2]	10,113	[1],[3]
Investments at value, cost	5,049	[1],[2]	9,991	[1],[3]
U.S. Treasury Securities [Member] | US Treasury Note [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,000	[1],[2]	10,000	[1],[3]
Description	U.S. Treasury Note	[1],[2]	U.S. Treasury Note	[1],[3]
Rate	1.75%	[1],[2]	2.00%	[1],[3]
Maturity	2022-05	[1],[2]	2021-11	[1],[3]
Fair Value	$ 5,045	[1],[2]	$ 10,113	[1],[3]

[1] See Note 2 in Notes to Consolidated Financial Statements.

[2] The table below shows the Company's long investment ratings from Moody's, Standard and Poor's, or Fitch, as well as the Company's long investments that were unrated but affiliated with Fannie Mae, Freddie Mac, or Ginnie Mae. Ratings tend to be a lagging credit indicator; as a result, the credit quality of the Company's long investment holdings may be lower than the credit quality implied based on the ratings listed below. In situations where an investment has a split rating, the lowest provided rating is used. The ratings descriptions include ratings qualified with a "+," "-," "1," "2" or "3." Percentage of Shareholders' Rating Description Equity U.S. Treasury Securities 1.27 % Unrated but Agency-Guaranteed 179.14 % Aaa/AAA/AAA 0.33 % Aa/AA/AA 0.57 % A/A/A 2.39 % Baa/BBB/BBB 2.82 % Ba/BB/BB or below 98.49 % Unrated 1.18 %

[3] The table below shows the Company's long investment ratings from Moody's, Standard and Poor's, or Fitch, as well as the Company's long investments that were unrated but affiliated with Fannie Mae, Freddie Mac, or Ginnie Mae. Ratings tend to be a lagging credit indicator; as a result, the credit quality of the Company's long investment holdings may be lower than the credit quality implied based on the ratings listed below. In situations where an investment has a split rating, the lowest provided rating is used. The ratings descriptions include ratings qualified with a "+," "-," "1," "2" or "3." Percentage of Rating Description Shareholders' Equity U.S. Treasury Securities 2.72 % Unrated but Agency-Guaranteed 206.07 % Aaa/AAA/AAA 1.25 % Aa/AA/AA 1.88 % A/A/A 5.44 % Baa/BBB/BBB 3.46 % Ba/BB/BB or below 103.36 % Unrated 2.71 %

[4] At June 30, 2012, the Company's long investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association represented 147.05%, 31.99%, and 0.10% of shareholders' equity, respectively.

[5] At December 31, 2011, the Company's long investments guaranteed by the Federal National Mortgage Association, the Federal Home Loan Mortgage Corporation, and the Government National Mortgage Association represented 142.04%, 63.62%, and 0.41% of shareholders' equity, respectively.

[6] Maturity date may be extended through November 4, 2015.