Financial Instruments and Fair Value Measurements - Carrying Amount and Fair Value (Details) - Nonrecurring - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Carrying Value
Financial instruments and fair value measurements
Debt	$ 297,199	$ 227,474
Fair Value
Financial instruments and fair value measurements
Debt	289,905	224,664
Level 1 | Carrying Value | U.S. Treasury Bills
Financial instruments and fair value measurements
Investments held by SPEs	4,802	5,132
Level 1 | Fair Value | U.S. Treasury Bills
Financial instruments and fair value measurements
Investments held by SPEs	4,814	5,475
Level 2 | Carrying Value | Fixed-rate debt
Financial instruments and fair value measurements
Debt	123,678	129,532
Level 2 | Carrying Value | Variable rate debt
Financial instruments and fair value measurements
Debt	173,521	97,942
Level 2 | Fair Value | Fixed-rate debt
Financial instruments and fair value measurements
Debt	116,384	126,722
Level 2 | Fair Value | Variable rate debt
Financial instruments and fair value measurements
Debt	173,521	97,942
Level 3 | Carrying Value
Financial instruments and fair value measurements
Debt	177,710	177,566
Level 3 | Carrying Value | Time deposit
Financial instruments and fair value measurements
Investments held by SPEs	200,000	200,000
Level 3 | Fair Value
Financial instruments and fair value measurements
Debt	187,389	204,802
Level 3 | Fair Value | Time deposit
Financial instruments and fair value measurements
Investments held by SPEs	$ 200,000	$ 200,000