Regulatory Authorities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011 ETC [Member] days	Dec. 31, 2011 EGL [Member]	Dec. 31, 2010 EGL [Member]
Regulatory Authorities [Line Items]
Maintenance of net capital, of aggregate indebtedness, percent	6.67%
Maintenance of net capital	$ 100		$ 67,893	$ 62,583
Regulatory net capital exceeding minimum net capital requirement			66,726	60,738
Tier 1 capital		5,000
Minimum liquid assets, amount		3,500
Days coverage of operating expenses, threshold		90
Collateral held in a segregated account at a third-party depository institution, threshold		$ 10,000