Marketable Securities Amortized Cost and Estimated Fair Value of Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Total
Cost	$ 29,763	$ 41,727
Gross Unrealized Gains	1,347	2,441
Gross Unrealized Losses	359	761
Fair Value	30,751	43,407
Securities Investments [Member]
Securities Investments
Cost	6,382	11,268
Gross Unrealized Gains	198	754
Gross Unrealized Losses	278	623
Fair Value	6,302	11,399
Debt Securities Carried by EGL [Member]
Other Securities
Cost	18,743	22,542
Gross Unrealized Gains	94	87
Gross Unrealized Losses	5	1
Fair Value	18,832	22,628
Mutual Funds [Member]
Other Securities
Cost	4,638	7,917
Gross Unrealized Gains	1,055	1,600
Gross Unrealized Losses	76	137
Fair Value	$ 5,617	$ 9,380