Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)			3 Months Ended
		Jan. 02, 2019	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Interest and/or penalties related to income tax matters			$ 0	$ 0
Operating lease liabilities	[1]		9,566,000
Operating right-of-use assets	[1]		7,738,000
ASU 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease liabilities					$ 9,900,000
Operating right-of-use assets			$ 8,057,000		$ 8,000,000
Cumulative-effect adjustment to retained earnings		$ 0
Equipment and Furnishings | Minimum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Equipment and furnishings, useful lives			3 years
Equipment and Furnishings | Maximum
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Equipment and furnishings, useful lives			10 years

[1] The adoption of ASU 2016-02, Leases (Topic 842) in the first quarter of 2019 resulted in the recognition of right-of-use assets and lease liabilities on balance sheet.