Fair Value Measurements - Summary of Placement in the Fair Value Hierarchy of Financial Assets that are Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States government debt securities	$ 8,996	$ 119,340
Equity securities		1,024
Other	264	585
Fair value of assets	9,260	120,949
Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States government debt securities	0	0
Equity securities		950
Other	0	0
Fair value of assets	0	950
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States government debt securities	8,996	119,340
Equity securities		74
Other	264	394
Fair value of assets	9,260	119,808
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States government debt securities	0	0
Equity securities		0
Other	0	191
Fair value of assets	$ 0	$ 191