Consolidated Condensed Schedule Of Investments (Financial Derivatives) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2012 item		Dec. 31, 2011 item
Investment Holdings, Other than Securities [Line Items]
Fair value	$ 74,304,000		$ 102,871,000
Fair Value	(28,680,000)		(27,040,000)
Financial derivatives - assets, cost	82,791,000		118,281,000
Derivatives, proceeds	(22,033,000)		(9,636,000)
Deutsche Bank Affiliates Dealer [Member]
Investment Holdings, Other than Securities [Line Items]
Swap assets held by dealer as a percentage of stockholders equity	6.69%		5.65%
Morgan Stanley Affiliates Dealer [Member]
Investment Holdings, Other than Securities [Line Items]
Swap assets held by dealer as a percentage of stockholders equity	5.68%		8.15%
Credit Suisse Affiliates Dealer [Member]
Investment Holdings, Other than Securities [Line Items]
Swap assets held by dealer as a percentage of stockholders equity			7.27%
Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Future contract	1		1
Future contract notional	1,000,000		1,000,000
Financial Derivatives - Assets [Member]
Investment Holdings, Other than Securities [Line Items]
Fair value	74,304,000	[1]	102,871,000	[1]
Investments owned as a percentage of net assets	18.80%	[1]	27.73%	[1]
Financial derivatives - assets, cost	82,791,000	[1]	118,281,000	[1]
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],[2],[3]
Notional value	7,797,000	[1],[2],[3]
Fair value	448,000	[1],[2],[3]
Financial derivatives - assets, cost	410,000	[1],[2],[3]
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	2036-07	[1],[2],[3]
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
Financial Derivatives - Assets [Member] | Long Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[3],[4]	Interest Rates	[1],[5],[6]
Notional value	1,700,000	[1],[3],[4]	4,500,000	[1],[5],[6]
Range of expiration dates	2017-05	[1],[3],[4]	2016-10	[1],[5],[6]
Fair value	14,000	[1],[3],[4]	68,000	[1],[5],[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],[3],[7]	Credit	[1],[5],[7]
Notional value	(46,828,000)	[1],[3],[7]	(74,787,000)	[1],[5],[7]
Fair value	38,759,000	[1],[3],[7]	61,498,000	[1],[5],[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],[3],[7]	2036-12	[1],[5],[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],[3],[7]	2034-09	[1],[5],[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],[3],[8]
Notional value	(112,390,000)	[1],[3],[8]
Fair value	34,764,000	[1],[3],[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	2052-10	[1],[3],[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	2037-08	[1],[3],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices ABX.HE AAA 2006-2 Index [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure			Credit	[1],[5],[8]
Notional value			(62,842,000)	[1],[5],[8]
Range of expiration dates			2046-05	[1],[5],[8]
Fair value			35,542,000	[1],[5],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices Other [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure			Credit	[1],[5],[8]
Notional value			(19,800,000)	[1],[5],[8]
Fair value			4,761,000	[1],[5],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices Other [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2052-10	[1],[5],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swap On Asset Backed Indices Other [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2049-03	[1],[5],[8]
Financial Derivatives - Assets [Member] | Short Credit Default Swaps On Corporate Bond Indices [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Credit	[1],[3],[9]	Credit	[1],[5],[9]
Notional value	(58,250,000)	[1],[3],[9]	(106,500,000)	[1],[5],[9]
Range of expiration dates	2017-06	[1],[3],[9]	2016-12	[1],[5],[9]
Fair value	316,000	[1],[3],[9]	963,000	[1],[5],[9]
Financial Derivatives - Assets [Member] | Short Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[10],[3]	Interest Rates	[1],[10],[5]
Notional value	(1,000,000)	[1],[10],[3]	(25,000,000)	[1],[10],[5]
Range of expiration dates	2022-06	[1],[10],[3]	2014-12	[1],[10],[5]
Fair value	3,000	[1],[10],[3]	27,000	[1],[10],[5]
Financial Derivatives - Assets [Member] | Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Fair value	74,304,000	[1],[3]	102,859,000	[1],[5]
Investments owned as a percentage of net assets	18.80%	[1],[3]	27.73%	[1],[5]
Financial derivatives - assets, cost	82,791,000	[1],[3]	118,281,000	[1],[5]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure			Interest Rates	[1],[11]
Notional value			(147,000,000)	[1],[11]
Fair value			12,000	[1],[11]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2013-09	[1],[11]
Financial Derivatives - Assets [Member] | Short Eurodollar Future [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates			2012-03	[1],[11]
Financial Derivatives - Assets [Member] | Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Fair value			12,000	[1]
Investments owned as a percentage of net assets			0.00%	[1]
Financial Derivatives - Liabilities [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(28,680,000)	[1]	(27,040,000)	[1]
Investments owned as a percentage of net assets	(7.26%)	[1]	(7.29%)	[1]
Derivatives, proceeds	(22,033,000)	[1]	(9,636,000)	[1]
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],[2]	Credit	[1],[2]
Notional value	69,370,000	[1],[2]	22,615,000	[1],[2]
Fair Value	(22,390,000)	[1],[2]	(9,548,000)	[1],[2]
Derivatives, proceeds	(21,632,000)	[1],[2]	(9,636,000)	[1],[2]
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	2051-02	[1],[2]	2051-02	[1],[2]
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	2037-08	[1],[2]	2036-06	[1],[2]
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	100,000	[1],[4]
Range of expiration dates	2022-07	[1],[4]
Fair Value	0	[1],[4]
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	(7,797,000)	[1],[8]
Fair Value	(448,000)	[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	2036-07	[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 Interest Rate Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[10]	Interest Rates	[1],[10]
Notional value	(248,900,000)	[1],[10]	(280,400,000)	[1],[10]
Fair Value	(5,535,000)	[1],[10]	(17,218,000)	[1],[10]
Financial Derivatives - Liabilities [Member] | Short Interest Rate Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2022-05	[1],[10]	2021-12	[1],[10]
Financial Derivatives - Liabilities [Member] | Short Interest Rate Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2014-04	[1],[10]	2014-04	[1],[10]
Financial Derivatives - Liabilities [Member] | Short Total Return Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Equity Market	[1],[12]	Equity Market	[1],[12]
Notional value	(22,304,000)	[1],[12]	(20,571,000)	[1],[12]
Fair Value	(253,000)	[1],[12]	(274,000)	[1],[12]
Financial Derivatives - Liabilities [Member] | Short Total Return Swaps [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2013-09	[1],[12]	2013-09	[1],[12]
Financial Derivatives - Liabilities [Member] | Short Total Return Swaps [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2012-09	[1],[12]	2012-09	[1],[12]
Financial Derivatives - Liabilities [Member] | Swaps [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	(28,626,000)	[1]	(27,040,000)	[1]
Investments owned as a percentage of net assets	(7.25%)	[1]	(7.29%)	[1]
Derivatives, proceeds	(22,033,000)	[1]	(9,636,000)	[1]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member]
Investment Holdings, Other than Securities [Line Items]
Primary risk exposure	Interest Rates	[1],[13]
Notional value	(105,000,000)	[1],[13]
Fair Value	(54,000)	[1],[13]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member] | Maximum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2013-09	[1]
Financial Derivatives - Liabilities [Member] | Short Eurodollar Future [Member] | Minimum [Member]
Investment Holdings, Other than Securities [Line Items]
Range of expiration dates	2012-09	[1],[13]
Financial Derivatives - Liabilities [Member] | Futures [Member]
Investment Holdings, Other than Securities [Line Items]
Fair Value	$ (54,000)	[1]
Investments owned as a percentage of net assets	(0.01%)	[1]

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

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

[3] The following table shows the Company's swap assets by dealer as a percentage of shareholders' equity: Percent of Shareholders' Dealer/Parent Company Equity Affiliates of Deutsche Bank 6.69 % Affiliates of Morgan Stanley 5.68 %

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

[5] The following table shows the Company's swap assets by dealer as a percentage of shareholders' equity: Percent of Dealer/Parent Company Shareholders' Equity Affiliates of Morgan Stanley 8.15 % Affiliates of Credit Suisse 7.27 % Affiliates of Deutsche Bank 5.65 %

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

[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 credit default swaps on corporate bond indices, the Company purchased protection.

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

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

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

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