Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
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Face (par) amount of debt instrument at time of issuance.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
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Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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- Definition

The cash inflow from a financial contract that meets the hedge criteria as either cash flow hedge, fair value hedge or hedge of net investment in foreign operations.

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-Publisher FASB
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Current period adjustment in other comprehensive income reflecting gains or losses on foreign currency transactions that are designated as, and are effective as, hedges of a net investment in a foreign entity, net of tax effect.

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Derivative Instruments, Hedging Activities and Fair Value (Details 3) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2021	Dec. 31, 2018	Dec. 31, 2016	Jan. 31, 2017
Foreign Currency Derivatives
Pre-tax net gains (losses) on certain loans designated as hedges of net investments in foreign subsidiaries	$ 7,600	$ (9,000)	$ 17,100	$ (29,300)
Proceeds from cross-currency interest rate swap termination			0	$ 16,625
Foreign currency forward exchange contracts
Foreign Currency Derivatives
U.S. Dollar Equivalent	675,492		675,492				$ 600,883
Recognized Gain (Loss)			(19,545)				1,394
Foreign currency forward exchange contracts \| British pounds sterling \| Sell
Foreign Currency Derivatives
U.S. Dollar Equivalent	70,207		70,207				55,120
Recognized Gain (Loss)			(807)				(228)
Foreign currency forward exchange contracts \| British pounds sterling \| Buy
Foreign Currency Derivatives
U.S. Dollar Equivalent	10,638		10,638				827
Recognized Gain (Loss)			17				(14)
Foreign currency forward exchange contracts \| Euros \| Sell
Foreign Currency Derivatives
U.S. Dollar Equivalent	317,163		317,163				326,797
Recognized Gain (Loss)			(19,028)				628
Foreign currency forward exchange contracts \| Euros \| Buy
Foreign Currency Derivatives
U.S. Dollar Equivalent	196,214		196,214				171,578
Recognized Gain (Loss)			792				(468)
Foreign currency forward exchange contracts \| Other currencies \| Sell
Foreign Currency Derivatives
U.S. Dollar Equivalent	50,692		50,692				43,455
Recognized Gain (Loss)			(758)				1,477
Foreign currency forward exchange contracts \| Other currencies \| Buy
Foreign Currency Derivatives
U.S. Dollar Equivalent	$ 30,578		30,578				3,106
Recognized Gain (Loss)			$ 239				$ (1)
Term Loan Facility, Fixed-Rate \| Term Loan
Foreign Currency Derivatives
Principal amount								$ 300,000
LIBOR \| Scenario, Forecast \| Term Loan Facility, Fixed-Rate \| Subsequent Event \| Term Loan
Foreign Currency Derivatives
Debt Instrument, Basis Spread on Variable Rate					2.71%	1.65%