Restricted Cash and Cash Equivalents - Reconciliation of Cash, Cash Equivalents and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Cash And Cash Equivalents [Abstract]
Cash and cash equivalents	$ 32,414	$ 32,463	$ 67,728
Restricted cash and cash equivalents - current	27,865		53,749
Restricted cash and investments - non-current	27,271	30,923	27,282
Less Restricted investments - non-current	(24,969)		(24,954)
Total cash, cash equivalents and restricted cash and cash equivalents shown in the statement of cash flows	$ 62,581	$ 67,472	$ 123,805	$ 84,472