Summary of Significant Accounting Policies - Activity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Accounting Policies [Abstract]
Finance Lease, Right-of-Use Asset, after Accumulated Amortization	$ 39,463		$ 39,463		$ 34,691
Operating Lease, Right-of-Use Asset	337,774		337,774		$ 337,842
Finance Lease, Right-of-Use Asset, Amortization	$ (921)	$ (874)	$ (2,404)	$ (2,446)