Revenue from Contracts with Customers - Contract Balances (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Revenue from Contracts with Customers
Accounts receivable, net	$ 98,426	$ 91,430
Contract assets - current	7,823	6,063
Contract assets - non-current	2,433	2,976
Contract assets - total	10,256	9,039
Contract liabilities - current	4,936	5,477
Contract liabilities - non-current	151	0
Contract liabilities - total	5,087	5,477
Station construction sales
Revenue from Contracts with Customers
Contract liabilities - current	4,900	5,500
Contract liabilities - non-current	$ 200	$ 0