Revenue Recognition - Contract Balances with Contract Customers (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts receivable, net	$ 2,524	$ 476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Other current assets	951	1,311
Billings on uncompleted contracts in excess of related costs	101	0
Other current liabilities	10,042	10,154
Contracts with Customers
Accounts receivable, net	2,524	476
Costs and estimated earnings in excess of billings on uncompleted contracts	0	987
Billings on uncompleted contracts in excess of related costs	101	0
Other current liabilities	$ 10,000	$ 10,000