Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jan. 01, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 691,915		$ 794,020
ASU 2016-09 Cumulative Effect Adjustment for Timing of Recognition of Excess Tax Benefits [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		$ 44,300
ASU 2016-09 Cumulative Effect of Actual Forfeiture Rate [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		(700)
Additional Paid in Capital		1,100
Deferred Tax Assets		$ (400)