Fair Value of Financial Instruments - Narrative (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net investment losses included in net income related to financial assets	$ (24,000)	$ 0
Net realized investment losses	(6,157,000)	4,745,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net investment losses included in net income related to financial assets	$ 0	0
Percentage of invested assets in total investment portfolio Level 3 recurring	5.90%
Net realized investment losses	$ (5,000,000.0)	$ (4,300,000)