Commitments and Contingencies - Lease Payments on Non-cancelable Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
Property Subject to or Available for Operating Lease [Line Items]
Present value of operating lease liabilities	$ 22,402	$ 22,400	$ 0
2019			1,222
2020			1,222
2021			1,222
2022			1,222
2023			1,222
Thereafter			55,689
Total			$ 61,799
Adoption of Topic 842 [Member]
Property Subject to or Available for Operating Lease [Line Items]
2019 (nine months remaining)	905
2020	1,217
2021	1,232
2022	1,248
2023	1,263
Thereafter	111,757
Total lease payments	117,622
Less: Imputed interest	(95,220)
Present value of operating lease liabilities	$ 22,402