Schedule II - Valuation and Qualifying Accounts (Details) - SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] | ||
| Balance at beginning of period | $ 144,619 | $ 104,976 |
| Charged to costs and expenses | 18,585 | 39,643 |
| Charge to other accounts | 0 | 0 |
| (Deductions) | 0 | 0 |
| Balance at end of period | $ 163,204 | $ 144,619 |