Summary of Significant Accounting Policies - Deferred Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Deferred lease costs capitalized-payroll and related costs	$ 1,343	$ 679	$ 6,007
Total deferred lease costs capitalized	$ 3,061	$ 5,142	$ 6,703