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Compensation Plans (Details) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2016 USD ($) shares | Mar. 31, 2015 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock-based compensation expense | $ 6,868 | $ 6,024
Performance Shares [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period | 3 years |
Stock-based compensation expense | $ 2,900 | 2,300
Unrecognized stock based compensation expense | 15,200 |
Restricted Stock Units (RSUs) [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Stock-based compensation expense | 3,200 | $ 2,900
Unrecognized stock based compensation expense | $ 15,400 |
Number of Shares Represented by Each RSU | shares | 1 |
Minimum [Member] | Performance Shares [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Multiplier Applied to PSU Awards at Settlement | 0 |
Maximum [Member] | Performance Shares [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Multiplier Applied to PSU Awards at Settlement | 2.00 |

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