Consolidated Statements of Partners' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Partnership distribution declared, per unit (in dollars per share)	$ 3.595	$ 3.455	$ 3.33
Cumulative Foreign Currency Translation Adjustment [Member]
Foreign currency translation adjustment, tax	$ 3,862	$ (4,330)	$ 2,127
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Unrealized loss on cash flow hedging derivatives, tax	$ (1,094)	$ (1,484)	$ (650)

Amount of tax expense (benefit), after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 220
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-Section 45
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Amount of tax expense (benefit), after reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
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The amount of the distribution per unit of limited partner interest.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
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