Fair Value Measurement - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Assets
Derivative asset	$ 0	$ 3,259
Liabilities
Derivative liability	0	10,677
Fair Value, Measurements, Recurring
Assets
Derivative asset	0	3,259
Equity securities - preferred stock investment	11,116
Liabilities
Derivative liability	0	10,677
Fair Value, Measurements, Recurring | Level 1
Assets
Derivative asset	0	0
Equity securities - preferred stock investment	0
Liabilities
Derivative liability	0	0
Fair Value, Measurements, Recurring | Level 2
Assets
Derivative asset	0	0
Equity securities - preferred stock investment	11,116
Liabilities
Derivative liability	0	0
Fair Value, Measurements, Recurring | Level 3
Assets
Derivative asset	0	3,259
Equity securities - preferred stock investment	0
Liabilities
Derivative liability	$ 0	$ 10,677