Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Lease Agreements and Long-term Principal and Interest on Convertible Notes (Parenthetical) (Details)	Jun. 30, 2018	Aug. 31, 2017	Jun. 30, 2017
3.75% Convertible Senior Notes due 2022
Debt
Interest rate (as a percent)	3.75%	3.75%	3.75%