Summary of Significant Accounting Policies - Adoption of ASU 2016-09 - Improvements to Employee Share-Based Payment Accounting (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement
Provision for income taxes	$ (56,207)	$ (40,290)	$ (99,289)	$ (83,719)
Statement of Cash Flows
Net cash provided by operating activities			400,792	339,081
Net cash used in financing activities			335,749	$ (2,170,196)
ASU 2016-09 Improvements to Employee Share-Based Payment Accounting | Excess tax benefits and deficiencies associated with share-based payments
Income Statement
Provision for income taxes			6,800
Statement of Cash Flows
Net cash provided by operating activities			6,800
Net cash used in financing activities			$ 6,800