Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2019 USD ($) Bank Segment	Dec. 31, 2018	Jan. 01, 2019 USD ($)
Schedule Of Significant Accounting Policies [Line Items]
Number of commercial banks | Bank	1
Number of operating segments | Segment	1
Estimated useful life	11 years
Expected dividend yield	0.00%	0.00%
Accounting Standards Update 2016-02 [Member]
Schedule Of Significant Accounting Policies [Line Items]
Present value of total fixed payments			$ 322,000
Right-of-use assets recognized			$ 301,000
Stock Options and Restricted Stock Units [Member]
Schedule Of Significant Accounting Policies [Line Items]
Vesting period	4 years
Stock Options [Member]
Schedule Of Significant Accounting Policies [Line Items]
Vesting period	4 years
Expected dividend yield	0.00%
Minimum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment	3 years
Maximum [Member]
Schedule Of Significant Accounting Policies [Line Items]
Estimated useful lives of property and equipment	5 years
Essentialis, Inc. [Member]
Schedule Of Significant Accounting Policies [Line Items]
Net intangible assets acquired	$ 22,000,000