Revenue Recognition - Contract Balances with Contract Customers (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounts receivable, net	$ 1,079	$ 476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Accrued liabilities	432	1,585
Deferred revenue	21	0
Contract liabilities	9,755	0
Other current liabilities	83	10,154
Other current assets	729	1,311
Billings on uncompleted contracts in excess of related costs	0	0
Contracts with Customers
Accounts receivable, net	1,079	476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Accrued liabilities	432	1,585
Deferred revenue	21	0
Contract liabilities	9,755	0
Other current liabilities	$ 0	$ 10,000