Basis and Summary of Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Effective income tax rate reconciliation, excess tax benefit, amount	$ 600
Net Cash Provided by (Used in) Operating Activities	104,179	$ 195,651
Net Cash Provided by (Used in) Financing Activities	$ (53,587)	(92,579)
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) 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		1,800
Net Cash Provided by (Used in) Financing Activities		$ (1,800)