Summary of Significant Accounting Policies - Fair Value Measurements (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Level 2
Fair Value, Net Asset (Liability) [Abstract]
Interest rate swaps	$ (1,523,000)
Fair value	(1,523,000)
Recurring basis | Level 1
Fair Value, Net Asset (Liability) [Abstract]
Cash equivalents	56,000	$ 448,000
Fair value	$ 56,000	448,000
Recurring basis | Level 2
Fair Value, Net Asset (Liability) [Abstract]
Interest rate swaps		(2,847,000)
Fair value		$ (2,847,000)