Fair Value Measurements - Principal Amount And Estimated Fair Value Of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Fair Value Measurements
Principal Amount	$ 270,913	$ 313,850
Fair Value	275,754	316,891
MARAD Debt (matures February 2027)
Fair Value Measurements
Principal Amount	40,913	48,850
Fair Value	40,496	52,481
2022 Notes (matured May 2022)
Fair Value Measurements
Principal Amount		35,000
Fair Value		34,794
2023 Notes (mature September 2023)
Fair Value Measurements
Principal Amount	30,000	30,000
Fair Value	29,504	29,054
2026 Notes (mature February 2026)
Fair Value Measurements
Principal Amount	200,000	200,000
Fair Value	$ 205,754	$ 200,562