Fair Value Disclosures (Investments Measured At Fair Value Based On Net Asset Value) (Additional Information) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Investments in managed funds	$ 523,872	$ 603,720
Equity Long/Short Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Amount redeemable	$ 44,500	$ 54,700
Funds Of Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments with no redemption provisions	98.00%	95.00%
Estimated period for the liquidation of the underlying assets	6 months
Funds subject to lockup [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investments prior notice period	45 days
Investments in managed funds	$ 340,700	$ 375,500
Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments in certain industries	99.00%	100.00%
Fixed Income and High Yield Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of funds being liquidated	9.00%	8.00%
Multi-asset Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Percentage of investments redeemable	12.00%	32.00%
Quarterly maximum withdrawal percentage	25.00%
Minimum [Member] | Equity Long/Short Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investments prior written notice period	30 days
Minimum [Member] | Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated period for the liquidation of the underlying assets	1 year
Minimum [Member] | Multi-asset Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investments prior written notice period	30 days
Maximum [Member] | Equity Long/Short Hedge Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investments prior written notice period	90 days
Maximum [Member] | Equity Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Estimated period for the liquidation of the underlying assets	8 years
Maximum [Member] | Multi-asset Funds [Member]
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Notice period redemption of investments prior written notice period	90 days