Fair Value Measurements - Summary of Changes in the Fair Values of Level 3 Assets Measured on a Recurring Basis (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Impairment	$ 0	$ (300,000)
Corporate debt securities | Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning of period	19,200,000	17,800,000
Impairment	0	(300,000)
Net valuation gain included in other comprehensive earnings	6,900,000	0
Fair value, end of period	$ 26,100,000	$ 17,500,000