Fair Value Measurement - Summary of interest rate collars (Details) - USD ($) $ in Millions	Jun. 30, 2019	May 31, 2019
Derivative [Line Items]
Notional Amount	$ 222.3	$ 222.3
LIBOR Ceiling	2.50%
Collar 1
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.20%
Collar 2
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.30%
Collar 3
Derivative [Line Items]
Notional Amount	$ 74.1
LIBOR Ceiling	2.50%
LIBOR Floor	1.40%