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Basis of Presentation and Consolidation (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016
Subsequent Event
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Capitalized Contract Cost, Net				$ 700,000
Retained Earnings \| Accounting Standards Update 2014-09 \| Subsequent Event
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption			$ 10,100,000
Retained Earnings \| Accounting Standards Update 2016-16
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative Effect of New Accounting Principle in Period of Adoption					$ 3,200,000
Escrow
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Restricted Cash	$ 0	$ 0			$ 30,000,000
Decrease in restricted cash	$ 6,200,000	$ 23,800,000