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Investments (Other Investment Portfolio by Strategy and the Remaining Commitment Amount Associated With Each Strategy) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Carrying Value	$ 135,560,000		$ 135,560,000		$ 137,865,000
Decrease in other investments			(2,300,000)
Net investment income earned	35,786,000	32,986,000	118,604,000	104,237,000
Energy/Power Generation [Member] | Alternative Investments [Member]
Carrying Value	30,792,000		30,792,000		35,560,000
Remaining Commitment	10,296,000		10,296,000
Net investment income earned	1,760,000	409,000	7,599,000	3,440,000
Secondary Private Equity Member | Alternative Investments [Member]
Carrying Value	29,077,000		29,077,000		26,709,000
Remaining Commitment	11,047,000		11,047,000
Net investment income earned	1,179,000	240,000	5,895,000	3,924,000
Private Equity [Member] | Alternative Investments [Member]
Carrying Value	21,067,000		21,067,000		21,601,000
Remaining Commitment	6,637,000		6,637,000
Net investment income earned	1,640,000	543,000	5,398,000	1,350,000
Distressed Debt [Member] | Alternative Investments [Member]
Carrying Value	19,285,000		19,285,000		20,432,000
Remaining Commitment	3,169,000		3,169,000
Net investment income earned	(153,000)	472,000	1,241,000	1,195,000
Real Estate Strategy [Member] | Alternative Investments [Member]
Carrying Value	14,033,000		14,033,000		14,192,000
Remaining Commitment	10,602,000		10,602,000
Net investment income earned	35,000	303,000	1,485,000	(2,056,000)
Mezzanine Financing [Member] | Alternative Investments [Member]
Carrying Value	9,993,000		9,993,000		10,230,000
Remaining Commitment	15,910,000		15,910,000
Net investment income earned	(133,000)	377,000	928,000	3,006,000
Venture Capital [Member] | Alternative Investments [Member]
Carrying Value	7,909,000		7,909,000		6,386,000
Remaining Commitment	900,000		900,000
Net investment income earned	125,000	15,000	1,448,000	263,000
Other Securities [Member]
Carrying Value	3,404,000		3,404,000		2,755,000
Remaining Commitment	2,096,000		2,096,000
Other Investments [Member]
Carrying Value	135,560,000		135,560,000		137,865,000
Remaining Commitment	60,657,000		60,657,000
Net investment income earned	4,494,000	2,400,000	24,082,000	11,216,000
Additional contributions			11,800,000
Alternative Investments [Member]
Carrying Value	132,156,000		132,156,000		135,110,000
Remaining Commitment	58,561,000		58,561,000
Distributions from alternative investments			37,900,000
Net investment income earned	$ 4,500,000	$ 2,300,000	$ 24,000,000	$ 11,100,000

X

- Definition

This item represents disclosure of the amount of distributions received from alternative investments. These investments are accounted for under the equity method of accounting.

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- Definition

This item represents the amount of funding that the company has provided on commitments in our other investment portfolio for the period.

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- Definition

This item represents the change in the carrying value of other investments.

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- Definition

The income earned from investments in securities and other investments including dividends, interest, and returns on other investments. This item does not include realized gains (losses).

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- Definition

This item represents contractual obligations to invest additional amounts on our other investment portfolio. These additional investments may or may not be required.

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- Definition

Other investments not otherwise specified in the taxonomy.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(f,g))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 12

-Article 5



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 1

-Subparagraph g



Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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