6. Derivative Financial Instruments (Details) - Summary - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Prepaid Expenses and Other Current Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	$ 2,299	$ 2,364
Prepaid Expenses and Other Current Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	230	158
Prepaid Expenses and Other Current Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,069	2,206
Other Assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	449
Other Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	449
Other Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0
Other Current Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(3,239)	(7,294)
Other Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	180	0
Other Current Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	3,059	7,294
Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets (Liabilities), at Fair Value, Net	(8,706)	(9,205)
Other Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Other Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	8,706	9,205
Foreign exchange forward contracts [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	230	158
Foreign exchange forward contracts [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	2,069	2,206
Foreign exchange forward contracts [Member] \| Other Assets [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	449
Foreign exchange forward contracts [Member] \| Other Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0
Foreign exchange forward contracts [Member] \| Other Current Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	180	0
Foreign exchange forward contracts [Member] \| Other Current Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	2,594	7,096
Foreign exchange forward contracts [Member] \| Other Liabilities [Member] \| Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Foreign exchange forward contracts [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	0	0
Interest rate swap contract [Member] \| Prepaid Expenses and Other Current Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0	0
Interest rate swap contract [Member] \| Other Assets [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	0
Interest rate swap contract [Member] \| Other Current Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	465	198
Interest rate swap contract [Member] \| Other Liabilities [Member] \| Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 8,706	$ 9,205

Fair values as of the balance sheet date of the net amount of all assets and liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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