Contract Assets and Liabilities Changes in Net Contract Assets (Liabilities) (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Contract assets
Contract asset, current	$ 791	$ 1,145
Contract asset, non-current	244	188
Contract asset	1,035	1,333
Contract Liabilities
Contract liability, current	7,595	5,963
Contract liability, non-current	1,154	1,401
Contract liabilities	$ 8,749	$ 7,364

Amount, after allowance for credit loss, of right to consideration in exchange for good or service transferred to customer when right is conditioned on something other than passage of time.

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