Significant Accounting Policies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended			3 Months Ended	6 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2014 Financial_Institution	Sep. 30, 2013	Sep. 30, 2014 Segment Financial_Institution	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Boost Issuer PLC [Member]	Sep. 30, 2014 Boost Issuer PLC [Member]	Sep. 30, 2014 WisdomTree Trust [Member]	Sep. 30, 2013 WisdomTree Trust [Member]	Sep. 30, 2014 WisdomTree Trust [Member]	Sep. 30, 2013 WisdomTree Trust [Member]
Related Party Transaction [Line Items]
Cash and cash equivalents maturity period, maximum			90 days
Number of financial institutions	1		1
Accounts receivable related-party	$ 15,471		$ 15,471		$ 14,791
ETF advisory fee revenue	$ 46,942	$ 39,437	$ 133,489	$ 105,691		$ 282	$ 467	$ 46,660	$ 39,437	$ 133,022	$ 105,691
Number of operating segments			1