Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Consolidated Balance Sheets [Abstract]
Accounts receivable, allowances	$ 198	$ 143
Property, and equipment, accumulated depreciation and amortization	$ 523,375	$ 530,194
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	56,452,866	47,470,505
Common stock, shares outstanding	44,639,705	35,657,344
Treasury stock, shares	11,813,161	11,813,161