Derivatives and Hedging Instruments - Fair Value of Derivative Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Foreign currency exchange contracts
Derivative [Line Items]
Foreign currency exchange contracts - assets		$ 1,912
Foreign currency exchange contracts - liabilities	$ (1,408)	(1,110)
Interest rate swap agreements
Derivative [Line Items]
Interest rate derivatives - assets	5
Interest rate derivative - liabilities		(7)
Interest rate cap contracts
Derivative [Line Items]
Interest rate derivatives - assets	2,445	3,922
Derivatives Designated as Hedging Instruments | Foreign currency exchange contracts | Other assets
Derivative [Line Items]
Foreign currency exchange contracts - assets	0	1,912
Derivatives Designated as Hedging Instruments | Foreign currency exchange contracts | Other liabilities
Derivative [Line Items]
Foreign currency exchange contracts - liabilities	(1,408)	0
Derivatives Designated as Hedging Instruments | Interest rate swap agreements | Other assets
Derivative [Line Items]
Interest rate derivatives - assets	5
Derivatives Designated as Hedging Instruments | Interest rate swap agreements | Other liabilities
Derivative [Line Items]
Interest rate derivative - liabilities		(7)
Derivatives Not Designated as Hedging Instruments | Foreign currency exchange contracts | Other liabilities
Derivative [Line Items]
Foreign currency exchange contracts - liabilities	0	(1,110)
Derivatives Not Designated as Hedging Instruments | Interest rate cap contracts | Other assets
Derivative [Line Items]
Interest rate derivatives - assets	$ 2,445	$ 3,922