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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities	$ 50,547	$ 62,818
Cash used in investing activities	$ 943,591	375,351
Accounting Standards Update 2016-18 and Accounting Standards Update 2016-15
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		62,818
Cash used in investing activities		375,351
Accounting Standards Update 2016-01 \| Cumulative other comprehensive loss
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle in period of adoption			$ (1,900)	$ (1,902)
Accounting Standards Update 2016-01 \| Cumulative net income
New Accounting Pronouncement, Early Adoption [Line Items]
Cumulative effect of new accounting principle in period of adoption			$ 1,900	$ 1,902
Originally Reported \| Accounting Standards Update 2016-18 and Accounting Standards Update 2016-15
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		64,326
Cash used in investing activities		372,718
Effect of Change \| Accounting Standards Update 2016-18 and Accounting Standards Update 2016-15
New Accounting Pronouncement, Early Adoption [Line Items]
Cash provided by operating activities		(1,508)
Cash used in investing activities		$ 2,633