Significant Accounting Policies - Performance Obligations (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2019 USD ($)
Significant Accounting Policies
Contracts with an original expected length	true
Remainder of 2019	$ 17,335
2020	52,951
2021	42,443
2022	31,951
2023	27,775
2024 and thereafter	54,159
Total	$ 226,614