Variable Interest Entity - Summary of Information about Variable Interests (Detail) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Carrying Amount - Assets
Total carrying amount - Assets	$ 36,284,000	$ 53,722,000
Maximum exposure to loss	36,284,000	53,722,000
Advisor Engine [Member]
Carrying Amount - Assets
Unsecured convertible notes receivable	2,126,000
Unsecured non-convertible note receivable	26,046,000	28,722,000
Preferred stock	0	25,000,000
Total carrying amount - Assets	28,172,000	$ 53,722,000
Securrency Inc [Member]
Carrying Amount - Assets
Preferred stock	$ 8,112,000