Consolidated Condensed Schedule Of Investments (Long Investments) (USD $) In Thousands, unless otherwise specified	9 Months Ended		12 Months Ended
	Sep. 30, 2012		Dec. 31, 2011
Schedule of Investments [Line Items]
Fair Value	$ 1,165,644		$ 1,212,483
Investments at value, cost	1,133,991		1,234,203
U.S. Treasury Securities [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity			2.72%
Unrated But Agency-Guaranteed [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	131.13%		206.07%
Long Investment AAA Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	0.02%		1.25%
Long Investment AA Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	0.45%		1.88%
Long Investment A Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	1.85%		5.44%
Long Investment BBB Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	8.25%		3.46%
Long Investment BB Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	90.44%		103.36%
Long Investment Unrated Rating [Member]
Schedule of Investments [Line Items]
Long investment holdings as a percentage of shareholders' equity	1.62%		2.71%
Long Investments [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	233.76%	[1],[2]	326.89%	[1],[3]
Fair Value	1,165,644	[1],[2]	1,212,483	[1],[3]
Investments at value, cost	1,133,991	[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	25.88%		63.62%
Long Investments [Member] | Government National Mortgage Association [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.67%		0.41%
Long Investments [Member] | Federal National Mortgage Association [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	104.58%		142.04%
Mortgage-Backed Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	232.83%	[1],[2]	322.98%	[1],[3]
Fair Value	1,160,994	[1],[2]	1,197,970	[1],[3]
Investments at value, cost	1,129,131	[1],[2]	1,219,423	[1],[3]
Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	131.13%	[1],[2],[4]	206.07%	[1],[3],[5]
Fair Value	653,873	[1],[2],[4]	764,344	[1],[3],[5]
Investments at value, cost	642,123	[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	127.00%	[1],[2],[4]	195.78%	[1],[3],[5]
Fair Value	633,290	[1],[2],[4]	726,160	[1],[3],[5]
Investments at value, cost	622,122	[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	119.50%	[1],[2],[4]	185.76%	[1],[3],[5]
Fair Value	595,906	[1],[2],[4]	689,018	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | 22,536 Federal National Mortgage Association Pool 4.50% 2041-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	22,536	[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	24,622	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 20,826 Federal National Mortgage Association Pool 3.50% 2042-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	20,826	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Fair Value	22,399	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2035-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,522	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2035-10	[1],[2],[4]
Fair Value	20,213	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,241	[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	20,012	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 18,327 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,327	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	19,735	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 17,926 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	17,926	[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	19,585	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 17,637 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	17,637	[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	19,270	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 15,981 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	15,981	[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	17,361	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 13,603 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	13,603	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	14,648	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 12,393 Federal National Mortgage Association Pool 4.50% 2041-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	12,393	[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	13,463	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 11,663 Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	11,663	[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	12,868	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	11,524	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	12,469	[1],[2],[4]
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	10,956	[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	11,822	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2042-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	9,599	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Fair Value	10,336	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.00% 2027-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	8,778	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.00%	[1],[2],[4]
Maturity	2027-08	[1],[2],[4]
Fair Value	9,311	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.00% 2027-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	7,097	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.00%	[1],[2],[4]
Maturity	2027-09	[1],[2],[4]
Fair Value	7,529	[1],[2],[4]
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	6,575	[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	7,213	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2034-03 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	6,141	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.00%	[1],[2],[4]
Maturity	2034-03	[1],[2],[4]
Fair Value	6,734	[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	5,989	[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	6,509	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,864	[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	6,396	[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	5,698	[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	6,215	[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	5,615	[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	6,092	[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	5,502	[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	6,029	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,550 Federal National Mortgage Association Pool 3.50% 2042-11 (Pre-Issue) [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,550	[1],[2],[4]
Description	Federal National Mortgage Association Pool (Pre-Issue)	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-11	[1],[2],[4]
Fair Value	6,004	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,569 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,569	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	5,974	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2042-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,240	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Fair Value	5,654	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 5,108 Federal National Mortgage Association Pool 4.00% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,108	[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	5,567	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2042-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,748	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-07	[1],[2],[4]
Fair Value	5,093	[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	4,450	[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	4,931	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 3.50% 2042-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,522	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-10	[1],[2],[4]
Fair Value	4,847	[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	4,487	[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	4,844	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,418 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,418	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	4,740	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 4,330 Federal National Mortgage Association Pool 3.50% 2027-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,330	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2027-06	[1],[2],[4]
Fair Value	4,640	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2041-11 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	4,087	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2041-11	[1],[2],[4]
Fair Value	4,416	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,923 Federal National Mortgage Association Pool 4.50% 2041-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,923	[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	4,261	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,946 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,946	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	4,234	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.50% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,778	[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	4,137	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,812 Federal National Mortgage Association Pool 3.50% 2027-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,812	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2027-06	[1],[2],[4]
Fair Value	4,085	[1],[2],[4]
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	3,676	[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	3,994	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation Pool 4.00% 2042-01 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,691	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-01	[1],[2],[4]
Fair Value	3,989	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,644 Federal National Mortgage Association Pool 3.50% 2042-11 (Pre-Issue) [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,644	[1],[2],[4]
Description	Federal National Mortgage Association Pool (Pre-Issue)	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-11	[1],[2],[4]
Fair Value	3,964	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,435 Federal National Mortgage Association Pool 4.00% 2042-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,435	[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	3,742	[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	3,307	[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	3,561	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,236 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,236	[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	3,526	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 3,196 Federal National Mortgage Association Pool 4.00% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,196	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	3,473	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,943 Federal National Mortgage Association Pool 4.00% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,943	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	3,206	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2027-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,995	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2027-07	[1],[2],[4]
Fair Value	3,205	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Government National Mortgage Association (Pre-Issue) 4.49% 2042-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,700	[1],[2],[4]
Description	Government National Mortgage Association (Pre-Issue)	[1],[2],[4]
Rate	4.49%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Fair Value	3,074	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,687 Federal National Mortgage Association Pool 4.50% 2041-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,687	[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	2,919	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 3.50% 2042-05 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,640	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-05	[1],[2],[4]
Fair Value	2,832	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,576 Federal National Mortgage Association Pool 4.00% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,576	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	2,798	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association Pool 4.00% 2042-09 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,508	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Fair Value	2,725	[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	2,516	[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	2,703	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | 2,509 Federal National Mortgage Association Pool 3.50% 2042-08 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,509	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	3.50%	[1],[2],[4]
Maturity	2042-08	[1],[2],[4]
Fair Value	2,701	[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 Home Loan Mortgage Corporation Pool 5.00% 2041-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	18,146	[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	19,894	[1],[2],[4]	20,417	[1],[3],[5]
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	16,201	[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	17,900	[1],[2],[4]	18,941	[1],[3],[5]
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	12,340	[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	13,343	[1],[2],[4]	14,252	[1],[3],[5]
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	10,112	[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	10,943	[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	8,591	[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	9,349	[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	9,039	[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	9,837	[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	8,169	[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	8,745	[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	7,822	[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	8,621	[1],[2],[4]	9,269	[1],[3],[5]
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	5,956	[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	6,564	[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] | Federal National Mortgage Association Pool 4.00% 2026-06 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,172	[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	5,536	[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	4,284	[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	4,722	[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	5,069	[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	5,561	[1],[2],[4]	5,985	[1],[3],[5]
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	4,964	[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	5,392	[1],[2],[4]	5,557	[1],[3],[5]
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	3,744	[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	4,108	[1],[2],[4]	5,209	[1],[3],[5]
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	3,672	[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	3,996	[1],[2],[4]	3,963	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal National Mortgage Association Pools [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	24,668	[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	26,867	[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	2042-09	[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	2027-08	[1],[2],[4]	2039-09	[1],[3],[5]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation Pools [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	7,268	[1],[2],[4]
Description	Other Federal Home Loan Mortgage Corporation Pools	[1],[2],[4]
Fair Value	7,858	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation Pools [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	6.00%	[1],[2],[4]
Maturity	2042-09	[1],[2],[4]
Principal And Interest - Fixed Rate Agency Securities [Member] | Other Federal Home Loan Mortgage Corporation Pools [Member] | Minimum [Member]
Schedule of Investments [Line Items]
Rate	3.00%	[1],[2],[4]
Maturity	2027-09	[1],[2],[4]
Interest Only - Fixed Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.74%	[1],[2],[4]	1.38%	[1],[3],[5]
Fair Value	3,661	[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	5,669	[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	282	[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	11,358	[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	1,214	[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	23,569	[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	2,165	[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	6.76%	[1],[2],[4]	8.64%	[1],[3],[5]
Fair Value	33,723	[1],[2],[4]	32,033	[1],[3],[5]
TBA - Fixed Rate Agency Securities [Member] | Federal Home Loan Mortgage Corporation (30 Year) 4.00% 2012-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	21,550	[1],[2],[4]
Description	Federal Home Loan Mortgage Corporation (30 Year)	[1],[2],[4]
Rate	4.00%	[1],[2],[4]
Maturity	2012-10	[1],[2],[4]
Fair Value	23,168	[1],[2],[4]
TBA - Fixed Rate Agency Securities [Member] | Federal National Mortgage Association (30 Year) 3.00% 2012-10 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	10,000	[1],[2],[4]
Description	Federal National Mortgage Association (30 Year)	[1],[2],[4]
Rate	3.00%	[1],[2],[4]
Maturity	2012-10	[1],[2],[4]
Fair Value	10,555	[1],[2],[4]
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]
Floating Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	4.13%	[1],[2],[4]	10.29%	[1],[3],[5]
Fair Value	20,583	[1],[2],[4]	38,184	[1],[3],[5]
Investments at value, cost	20,001	[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	4.10%	[1],[2],[4]	10.23%	[1],[3],[5]
Fair Value	20,417	[1],[2],[4]	37,956	[1],[3],[5]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.24% 2035-12 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,358	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.24%	[1],[2],[4]
Maturity	2035-12	[1],[2],[4]
Fair Value	5,650	[1],[2],[4]
Principal And Interest - Floating Rate Agency Securities [Member] | Federal National Mortgage Association Pool 5.50% 2037-07 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	2,712	[1],[2],[4]
Description	Federal National Mortgage Association Pool	[1],[2],[4]
Rate	5.50%	[1],[2],[4]
Maturity	2037-07	[1],[2],[4]
Fair Value	2,912	[1],[2],[4]
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	7,115	[1],[2],[4]	9,464	[1],[3],[5]
Description	Federal National Mortgage Association Pool	[1],[2],[4]	Federal National Mortgage Association Pool	[1],[3],[5]
Rate	5.10%	[1],[2],[4]	5.10%	[1],[3],[5]
Maturity	2038-05	[1],[2],[4]	2038-05	[1],[3],[5]
Fair Value	7,501	[1],[2],[4]	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 5.69% 2036-04 [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	3,034	[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	3,218	[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	1,066	[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	1,136	[1],[2],[4]
Interest Only - Floating Rate Agency Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.03%	[1],[2],[4]	0.06%	[1],[3],[5]
Fair Value	166	[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	1,155	[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	166	[1],[2],[4]	228	[1],[3],[5]
Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	101.70%	[1],[2]	116.91%	[1],[3]
Fair Value	507,121	[1],[2]	433,626	[1],[3]
Investments at value, cost	487,008	[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	101.02%	[1],[2]	114.91%	[1],[3]
Fair Value	503,745	[1],[2]	426,202	[1],[3]
Investments at value, cost	483,548	[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	824,471	[1],[2]	762,480	[1],[3]
Description	Various	[1],[2]	Various	[1],[3]
Fair Value	503,745	[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	0.28%	[1],[2]	0.35%
Maturity	2019-05	[1],[2]	2019-05	[1],[3]
Principal Only - Private Label Securities [Member]
Schedule of Investments [Line Items]
Investments owned as a percentage of net assets	0.43%	[1],[2]
Fair Value	2,146	[1],[2]
Investments at value, cost	2,189	[1],[2]
Principal Only - Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	5,800	[1],[2]
Description	Various	[1],[2]
Rate	0.00%	[1],[2]
Maturity	2030-08	[1],[2]
Fair Value	2,146	[1],[2]
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	1,230	[1],[2]	1,774	[1],[3]
Investments at value, cost	796	[1],[2]	1,471	[1],[3]
Interest Only - Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	65,872	[1],[2]	76,167	[1],[3]
Description	Various	[1],[2]	Various	[1],[3]
Fair Value	1,230	[1],[2]	1,774	[1],[3]
Interest Only - Private Label Securities [Member] | Various Issuer [Member] | Maximum [Member]
Schedule of Investments [Line Items]
Rate	2.00%	[1],[2]	6.91%	[1],[3]
Maturity	2047-09	[1],[2]	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	2044-06	[1],[2]	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	475	[1],[2]	6,011	[1],[3]
Other Private Label Securities [Member] | Various Issuer [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount	175,151	[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	0.93%	[1],[2],[6]	1.19%	[1],[3],[6]
Fair Value	4,650	[1],[2],[6]	4,400	[1],[3],[6]
Investments at value, cost	4,860	[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	2013-11	[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			2.72%	[1],[3]
Fair Value			10,113	[1],[3]
Investments at value, cost			9,991	[1],[3]
U.S. Treasury Securities [Member] | US Treasury Note [Member]
Schedule of Investments [Line Items]
Current Principal/Notional Amount			10,000	[1],[3]
Description			U.S. Treasury Note	[1],[3]
Rate			2.00%	[1],[3]
Maturity			2021-11	[1],[3]
Fair Value			$ 10,113	[1],[3]

[1] See Note 2 and Note 3 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 Unrated but Agency-Guaranteed 131.13 % Aaa/AAA/AAA 0.02 % Aa/AA/AA 0.45 % A/A/A 1.85 % Baa/BBB/BBB 8.25 % Ba/BB/BB or below 90.44 % Unrated 1.62 %

[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 September 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 104.58%, 25.88%, and 0.67% 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.