Derivatives and Hedging - Outstanding Derivatives Contracts (Details) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2019 USD ($) derivative_instrument outstanding_contract	Dec. 31, 2018 USD ($) outstanding_contract
Derivatives, Fair Value [Line Items]
Number of Contracts \| outstanding_contract	63	142
Notional Amounts	$ 2,395,509	$ 3,027,375
Fair Value Asset (Liability), Net	(30,972)	(12,623)
Unrealized Loss Recorded in AOCI/L	$ (22,275)	$ (7,770)
Interest rate swaps
Derivatives, Fair Value [Line Items]
Number of Contracts \| derivative_instrument	5,000,000
Notional Amounts	$ 1,400,000
Designated as hedging instrument \| Other liabilities \| Interest rate swaps
Derivatives, Fair Value [Line Items]
Number of Contracts \| outstanding_contract	7	7
Notional Amounts	$ 2,100,000	$ 2,100,000
Fair Value Asset (Liability), Net	(30,618)	(10,681)
Unrealized Loss Recorded in AOCI/L	$ (22,275)	$ (7,770)
Not Designated as Hedging Instrument \| Accrued liabilities \| Foreign currency forwards
Derivatives, Fair Value [Line Items]
Number of Contracts \| outstanding_contract	56	135
Notional Amounts	$ 295,509	$ 927,375
Fair Value Asset (Liability), Net	(354)	(1,942)
Unrealized Loss Recorded in AOCI/L	$ 0	$ 0

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
-Article 12
-Section 13
-Sentence Column B

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+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 45
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The number of derivative instruments of a particular group held by the entity.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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