Business and Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash provided by operating activities	$ (159,135)	$ (467,236)	$ (167,552)
Cash provided by (used in) financing activities	(211,397)	(153,663)	(47,309)
Effective income tax rate reconciliation, excess tax benefit, amount	1,100
Retained Earnings	1,819,524	1,534,983
Pro Forma | Accounting Standards Update 2014-09, Revenue From Contracts With Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Deferred revenue				$ 2,400
Adjustments for New Accounting Pronouncement | Accounting Standards Update 2016-09, Excess Tax Benefit Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash provided by operating activities		(700)	(300)
Cash provided by (used in) financing activities	700	300
Adjustments for New Accounting Pronouncement | Accounting Standards Update 2016-09, Statutory Tax Withholding Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash provided by operating activities		(2,500)	$ (400)
Cash provided by (used in) financing activities	$ (2,500)	$ (400)
Difference between Revenue Guidance in Effect before and after Topic 606 | Pro Forma | Accounting Standards Update 2014-09, Revenue From Contracts With Customers
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained Earnings				$ 2,400