Commitment and Contingencies - Estimated Unconditional Purchase Obligations (Details) $ in Thousands	Sep. 30, 2019 USD ($)
Recorded Unconditional Purchase Obligation [Line Items]
2019 (excluding the nine months ended September 30, 2019)	$ 123
2020	123
2021	705
2022	9,012
2023	7,363
Thereafter	13,420
Total	30,746
Connectivity Agreement
Recorded Unconditional Purchase Obligation [Line Items]
2019 (excluding the nine months ended September 30, 2019)	123
2020	123
2021	369
2022	0
2023	0
Thereafter	0
Total	615
Credit Voucher Agreement
Recorded Unconditional Purchase Obligation [Line Items]
2019 (excluding the nine months ended September 30, 2019)	0
2020	0
2021	336
2022	9,012
2023	7,363
Thereafter	13,420
Total	$ 30,131