Fair Value Measurements - Assets and Liabilities Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets:
Investments	$ 286,210	$ 234,178
Total	418,752	466,078
Deposits held with banks
Assets:
Cash and cash equivalents:	113,268	214,702
Short-term highly liquid investments
Assets:
Cash and cash equivalents:	19,274	17,198
Level 1
Assets:
Investments	152,295	206,724
Total	284,837	438,624
Level 1 \| Deposits held with banks
Assets:
Cash and cash equivalents:	113,268	214,702
Level 1 \| Short-term highly liquid investments
Assets:
Cash and cash equivalents:	19,274	17,198
Level 2
Assets:
Investments	133,915	27,454
Total	133,915	27,454
Level 2 \| Deposits held with banks
Assets:
Cash and cash equivalents:	0	0
Level 2 \| Short-term highly liquid investments
Assets:
Cash and cash equivalents:	0	0
Level 3
Assets:
Investments	0	0
Total	0	0
Level 3 \| Deposits held with banks
Assets:
Cash and cash equivalents:	0	0
Level 3 \| Short-term highly liquid investments
Assets:
Cash and cash equivalents:	$ 0	$ 0