Marketable Securities Amortized Cost and Estimated Fair Value of Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Total
Cost	$ 41,727	$ 34,640
Gross Unrealized Gains	2,441	1,937
Gross Unrealized Losses	761	32
Fair Value	43,407	36,545
Securities Investments [Member]
Securities Investments
Cost	11,268	10,172
Gross Unrealized Gains	754	1,428
Gross Unrealized Losses	623	20
Fair Value	11,399	11,580
Debt Securities Carried by EGL [Member]
Other Securities
Cost	22,542	13,522
Gross Unrealized Gains	87	97
Gross Unrealized Losses	1	0
Fair Value	22,628	13,619
Mutual Funds [Member]
Other Securities
Cost	7,917	10,946
Gross Unrealized Gains	1,600	412
Gross Unrealized Losses	137	12
Fair Value	$ 9,380	$ 11,346