Summary of Significant Accounting Policies - Fair Value Measurements (Details) - Fair Value, Measurements, Recurring - Significant Unobservable Inputs (Level 3) $ in Thousands	Mar. 31, 2018 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 0
Liabilities measured at fair value	$ 0