Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) item Liability	Dec. 31, 2016 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Number of counterparties, which experienced significant downgrades | item	0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets		$ 0
Liabilities		0
Fair value measurement with unobservable inputs reconciliation, number of liabilities | Liability	1
Level 3 | OPM Acquisition
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Acquisition of fair value liabilities, contingent consideration	$ 2,900,000
Level 2 | Fair Value Measured on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	16,700,000	12,000,000
Derivative liabilities	3,300,000	$ 34,300,000
Level 2 | Fair Value Measured on Recurring Basis | Interest Rate Swap Agreements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	800,000
Derivative liabilities	$ 400,000
Derivative assets and liabilities measurement valuation	Interest rate swap — valued using LIBOR yield curves at the reporting date.
Level 2 | Fair Value Measured on Recurring Basis | Foreign Currency Forward Exchange Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	$ 16,000,000
Derivative liabilities	$ 2,900,000
Derivative assets and liabilities measurement valuation	Foreign exchange derivative assets and liabilities — valued using quoted forward foreign exchange prices at the reporting date.