Fair Value Measurements (Narrative) (Detail)	9 Months Ended
	Sep. 30, 2015
Redemption Notice Periods Lower Range [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice period for redemption for alternative investments investment funds, days	5 days
Redemption Notice Periods Upper Range [Member]
Fair Value Measurements Of Financial Instruments [Line Items]
Notice period for redemption for alternative investments investment funds, days	120 days