Financial Instruments and Fair Value Measurement - Interest Rate Risk (Details) $ in Millions	Mar. 31, 2018 USD ($)
Interest Swap Position One
Derivative [Line Items]
Notional amount of derivative	$ 250.0
Weighted Average Interest Rate	1.16%
Interest Swap Position Two
Derivative [Line Items]
Notional amount of derivative	$ 150.0
Weighted Average Interest Rate	2.03%
Interest Swap Position Three
Derivative [Line Items]
Notional amount of derivative	$ 150.0
Weighted Average Interest Rate	2.25%
Interest Swap Position Four
Derivative [Line Items]
Notional amount of derivative	$ 150.0
Weighted Average Interest Rate	2.36%