Fair Value of Financial Instruments - Narrative (Details) - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2018	Dec. 31, 2020	Apr. 04, 2018	Mar. 27, 2018
Debt Instrument [Line Items]
Proceeds from issuance of notes	$ 0	$ 4,791,000
Unsecured obligations
Debt Instrument [Line Items]
Aggregate principal amount	5,300,000
Unsecured obligations | 2.50% Convertible notes due 2023
Debt Instrument [Line Items]
Proceeds from issuance of notes			$ 171,500,000
Fair value	$ 112,700,000			$ 98,700,000
Aggregate principal amount					$ 171,500,000	$ 150,000,000.0