Investments (Summary Of Investments In Private Equity Funds) (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	$ 26,483	$ 25,151
ECP II [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	4,357	5,037
Discovery Fund [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	2,594	2,393
EMCP II [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	11,123	9,674
Emcp III [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	749
CSI Capital [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	2,259	3,496
Trilantic IV [Member]
Schedule Of Investments In Private Equity Funds [Line Items]
Total Private Equity Funds	$ 5,401	$ 4,551