Consolidated VIEs - Summary of Consolidated VIE Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 1,109,745	$ 1,231,593
Customers and other receivables	106,746	125,696
Investments	535,245	531,995
Other assets	329,907	257,199
Total Assets	5,466,997	5,639,581
Liabilities:
Deposits and other customer payables	1,244,562	1,246,200
Other liabilities	476,748	534,268
Total Liabilities	4,688,299	4,958,007
Consolidated VIEs [Member]
ASSETS
Cash and cash equivalents	3,848	3,826
Customers and other receivables	1,061	102
Investments	154,454	97,474
Other assets	397	245
Total Assets	159,760	101,647
Liabilities:
Deposits and other customer payables	215	62
Other liabilities	985	513
Total Liabilities	$ 1,200	$ 575