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Basis of Presentation, Significant Accounting Policies, and Recently Issued Accounting Standards Recently Issued Accounting Standards (Details) - USD ($) $ in Thousands | Jun. 30, 2017 | Jan. 01, 2017 | Dec. 31, 2016
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New Accounting Pronouncements or Change in Accounting Principle [Line Items] |  |  |
Retained earnings | $ 786,608 |  | $ 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) |

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