Basis and Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate reconciliation, excess tax benefit, amount	$ 1,000
Net cash provided by (used in) operating activities	180,273	$ 461,787
Net cash provided by (used in) in financing activities	$ (176,899)	(153,252)
Adjustments for New Accounting Pronouncement | Accounting Standards Update 2016-09, Excess Tax Benefit Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		700
Net cash provided by (used in) in financing activities		(700)
Adjustments for New Accounting Pronouncement | Accounting Standards Update 2016-09, Statutory Tax Withholding Component
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash provided by (used in) operating activities		2,000
Net cash provided by (used in) in financing activities		$ (2,000)