Basis of Presentation and Significant Accounting Policies (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Employee Service Share-based Compensation, Tax Benefit from Compensation Expense	$ 400		$ 4,000
Tax paid for net share exercises and issuance of vested restricted stock units				$ 1,600
Payments Related to Tax Withholding for Share-based Compensation			$ 9,505	$ 5,775
Weighted Average Number Diluted Shares Outstanding Adjustment		215	211