Revenues - Contract Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Short-term unbilled receivables	$ 11,707	$ 9,191
Long-term unbilled receivables	12,260	16,481
Total contract assets	23,967	25,672
Short-term deferred revenues, net	90,894	81,835
Long-term deferred revenues	7,083	10,582
Total contract liabilities	$ 97,977	$ 92,417