Consolidated Condensed Schedule Of Investments (Financial Derivatives) (USD $)	9 Months Ended		12 Months Ended
	Sep. 30, 2013 contracts		Dec. 31, 2012 contracts
Investment Holdings, Other than Securities [Line Items]
Derivative Assets	$ 43,567,000		$ 48,504,000
Fair Value	(33,457,000)		(15,212,000)
Financial derivatives - cost	43,199,000		65,860,000
Financial derivatives - proceeds	(28,271,000)		(13,171,000)
U.S. Treasury Note Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Number of contracts	1,629
Eurodollar Future [Member]
Investment Holdings, Other than Securities [Line Items]
Future contract notional	1,000,000		1,000,000
Future contract	1		1
Financial Derivatives - Assets [Member]
Investment Holdings, Other than Securities [Line Items]
Derivative Assets	43,567,000	[1],[2]	48,504,000	[1],[2]
Investment owned as a percentage of net assets	6.92%	[1],[3]	9.58%	[1],[3]
Financial derivatives - cost	43,199,000	[1]	65,860,000	[1]
Financial Derivatives - Assets [Member] | Long Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[4]
Notional value	187,700,000	[1],[4]
Derivative Assets	2,968,000	[1],[4]
Financial Derivatives - Assets [Member] | Long Interest Rate Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2018-07	[1],[4]
Financial Derivatives - Assets [Member] | Long Interest Rate Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2043-07	[1],[4]
Financial Derivatives - Assets [Member] | Long Credit Default Swap On Asset Backed Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[5]	Credit	[1],[5]
Notional value	2,072,000	[1],[5]	10,166,000	[1],[5]
Range of expiration dates	2037-12	[1],[5]
Derivative Assets	62,000	[1],[5]	765,000	[1],[5]
Financial derivatives - cost			135,000	[1],[5]
Financial derivatives - proceeds	(217,000)	[1],[5]
Financial Derivatives - Assets [Member] | Long Credit Default Swap On Asset Backed Indices [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2036-06	[1],[5]
Financial Derivatives - Assets [Member] | Long Credit Default Swap On Asset Backed Indices [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2037-12	[1],[5]
Financial Derivatives - Assets [Member] | Long Total Return Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Equity Market	[1],[6]
Notional value	4,548,000	[1],[6]
Derivative Assets	14,000	[1],[6]
Financial Derivatives - Assets [Member] | Long Total Return Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2014-03	[1],[6]
Financial Derivatives - Assets [Member] | Long Total Return Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2015-06	[1],[6]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Securities [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[7]	Credit	[1],[7]
Notional value	(24,737,000)	[1],[7]	(42,121,000)	[1],[7]
Derivative Assets	17,615,000	[1],[7]	36,031,000	[1],[7]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Securities [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2034-09	[1],[7]	2034-09	[1],[7]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Securities [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2036-05	[1],[7]	2036-05	[1],[7]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[8]	Credit	[1],[8]
Notional value	(78,488,000)	[1],[8]	(66,829,000)	[1],[8]
Derivative Assets	9,122,000	[1],[8]	11,703,000	[1],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2046-05	[1],[8]	2046-05	[1],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2063-05	[1],[8]	2052-10	[1],[8]
Financial Derivatives - Assets [Member] | Short Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[9]	Interest Rates	[1],[9]
Notional value	(582,100,000)	[1],[9]	(18,900,000)	[1],[9]
Range of expiration dates			2017-10	[1],[9]
Derivative Assets	12,805,000	[1],[9]	5,000	[1],[9]
Financial Derivatives - Assets [Member] | Short Interest Rate Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2016-01	[1],[9]
Financial Derivatives - Assets [Member] | Short Interest Rate Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2043-07	[1],[9]
Financial Derivatives - Assets [Member] | Short Total Return Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Equity Market	[1],[6]
Notional value	(2,624,000)	[1],[6]
Range of expiration dates	2014-09	[1],[5]
Derivative Assets	1,000	[1],[6]
Financial Derivatives - Assets [Member] | Swap [Member]
Investment Holdings, Other than Securities [Line Items]
Derivative Assets	42,587,000	[1]	48,504,000	[1]
Investment owned as a percentage of net assets	6.76%	[1],[3]	9.58%	[1],[3]
Financial derivatives - cost	43,154,000	[1]	65,860,000	[1]
Financial Derivatives - Assets [Member] | Long US Treasury Note Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[10]
Notional value	208,100,000	[1],[10]
Range of expiration dates	2013-12	[1],[10]
Derivative Assets	976,000	[1],[10]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[11]
Notional value	(6,000,000)	[1],[11]
Derivative Assets	0	[1],[11]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2013-12	[1],[11]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2014-06	[1],[11]
Financial Derivatives - Assets [Member] | Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Derivative Assets	976,000	[1]
Investment owned as a percentage of net assets	0.16%	[1],[3]
Financial Derivatives - Assets [Member] | TBA Put Options Purchased [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[12]
Notional value	3,700,000	[1],[12]
Range of expiration dates	2013-11	[1],[12]
Derivative Assets	4,000	[1],[12]
Financial Derivatives - Assets [Member] | Put Option [Member]
Investment Holdings, Other than Securities [Line Items]
Derivative Assets	4,000	[1]
Investment owned as a percentage of net assets	0.00%	[1],[3]
Financial derivatives - cost	45,000	[1]
Financial Derivatives - Liabilities [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(33,457,000)	[1],[2]	(15,212,000)	[1],[2]
Investment owned as a percentage of net assets	(5.31%)	[1],[3]	(3.00%)	[1],[3]
Financial derivatives - proceeds	(28,271,000)	[1]	(13,171,000)	[1]
Financial Derivatives - Liabilities [Member] | Long Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure			Interest Rates	[1],[4]
Notional value			2,500,000	[1],[4]
Fair Value			(32,000)	[1],[4]
Financial Derivatives - Liabilities [Member] | Long Interest Rate Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2022-11	[1],[4]
Financial Derivatives - Liabilities [Member] | Long Interest Rate Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2022-12	[1],[4]
Financial Derivatives - Liabilities [Member] | Long Credit Default Swap On Asset Backed Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[5]	Credit	[1],[5]
Notional value	62,708,000	[1],[5]	30,050,000	[1],[5]
Fair Value	(19,310,000)	[1],[5]	(12,751,000)	[1],[5]
Financial derivatives - proceeds	(20,679,000)	[1],[5]	(12,736,000)	[1],[5]
Financial Derivatives - Liabilities [Member] | Long Credit Default Swap On Asset Backed Indices [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2049-12	[1],[5]	2049-12	[1],[5]
Financial Derivatives - Liabilities [Member] | Long Credit Default Swap On Asset Backed Indices [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2052-10	[1],[5]	2051-02	[1],[5]
Financial Derivatives - Liabilities [Member] | Long Total Return Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Equity Market	[1],[6]
Notional value	30,084,000	[1],[6]
Fair Value	(22,000)	[1],[6]
Financial Derivatives - Liabilities [Member] | Long Total Return Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2014-03	[1],[6]
Financial Derivatives - Liabilities [Member] | Long Total Return Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2015-06	[1],[6]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swap On Asset Backed Securities [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[7]	Credit	[1],[7]
Notional value	(3,000,000)	[1],[7]	(3,000,000)	[1],[7]
Range of expiration dates	2035-03	[1],[7]	2035-03	[1],[7]
Fair Value	(319,000)	[1],[7]	(1,000)	[1],[7]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swap On Asset Backed Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure			Credit	[1],[8]
Notional value			(7,792,000)	[1],[8]
Fair Value			(717,000)	[1],[8]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swap On Asset Backed Indices [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2036-06	[1],[8]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swap On Asset Backed Indices [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2037-12	[1],[8]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swaps On Corporate Bond Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[13]	Credit	[1],[13]
Notional value	(182,713,000)	[1],[13]	(67,500,000)	[1],[13]
Range of expiration dates			2017-12	[1],[13]
Fair Value	(9,679,000)	[1],[13]	(484,000)	[1],[13]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swaps On Corporate Bond Indices [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2017-12	[1],[13]
Financial Derivatives - Liabilities [Member] | Short Credit Default Swaps On Corporate Bond Indices [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2018-12	[1],[13]
Financial Derivatives - Liabilities [Member] | Short Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[9]	Interest Rates	[1],[9]
Notional value	(399,800,000)	[1],[9]	(220,000,000)	[1],[9]
Fair Value	(4,122,000)	[1],[9]	(1,092,000)	[1],[9]
Financial Derivatives - Liabilities [Member] | Short Interest Rate Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2015-03	[1],[13]	2014-08	[1],[9]
Financial Derivatives - Liabilities [Member] | Short Interest Rate Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2043-09	[1],[13]	2022-11	[1],[9]
Financial Derivatives - Liabilities [Member] | Short Total Return Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Equity Market	[1],[6]	Equity Market	[1],[6]
Notional value	(6,793,000)	[1],[6]	(18,737,000)	[1],[6]
Range of expiration dates	2015-09	[1],[6]	2013-09	[1],[6]
Fair Value	0	[1],[6]	(65,000)	[1],[6]
Financial Derivatives - Liabilities [Member] | Swap [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(33,452,000)	[1]	(15,142,000)	[1]
Investment owned as a percentage of net assets	(5.31%)	[1],[3]	(2.99%)	[1],[3]
Financial derivatives - proceeds	(28,222,000)	[1]	(13,171,000)	[1]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[11]	Interest Rates	[1],[11]
Notional value	(10,000,000)	[1],[11]	(63,000,000)	[1],[11]
Range of expiration dates	2015-09	[1],[11]
Fair Value	(1,000)	[1],[11]	(70,000)	[1],[11]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2013-03	[1],[11]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2013-09	[1],[11]
Financial Derivatives - Liabilities [Member] | Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(1,000)	[1]	(70,000)	[1]
Investment owned as a percentage of net assets	0.00%	[1],[3]	(0.01%)	[1],[3]
Financial Derivatives - Liabilities [Member] | TBA Put Options Written [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[12]
Notional value	(3,700,000)	[1],[12]
Range of expiration dates	2013-11	[1],[12]
Fair Value	(4,000)	[1],[12]
Financial Derivatives - Liabilities [Member] | Put Option [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(4,000)	[1]
Investment owned as a percentage of net assets	0.00%	[1],[3]
Financial derivatives - proceeds	$ (49,000)	[1]

[1] See Note 2 and Note 3 in Notes to Consolidated Financial Statements.

[2] In the Company's Consolidated Statement of Assets, Liabilities, and Equity, all balances associated with the repurchase agreements, reverse repurchase agreements, and derivatives transactions are presented on a gross basis.

[3] Classification percentages are based on Total Equity.

[4] For long interest rate swap contracts, a floating rate is being paid and a fixed rate is being received.

[5] For long credit default swaps on asset-backed indices, the Company sold protection.

[6] Notional value represents number of underlying shares or par value times the closing price of the underlying security.

[7] For short credit default swaps on asset-backed securities, the Company purchased protection.

[8] For short credit default swaps on asset-backed indices, the Company purchased protection.

[9] For short interest rate swap contracts, a fixed rate is being paid and a floating rate is being received.

[10] Notional value represents the total face amount of U.S. Treasury Notes underlying all contracts held; as of September 30, 2013 1,629 contracts were held.

[11] Every $1,000,000 in notional value represents one contract.

[12] Notional amount represents total face amount of TBA securities underlying each option contract.

[13] For short credit default swaps on corporate bond indices, the Company purchased protection.