Leases (Supplemental Balance Sheet Information Related to Leases) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Leases, Operating [Abstract]
Operating lease right-of-use assets	$ 20,342	$ 34,099
Operating lease liabilities - current	1,350	6,901
Operating lease liabilities - long-term	19,460	41,932
Total operating lease liabilities	$ 20,810	$ 48,833