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Capital Stock and Share-Based Compensation - Restricted Stock Units Issued and Outstanding (Details) - 2010 Incentive Award Plan - Restricted Stock Units (RSUs)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2017
USD ($)
$ / shares
shares
Restricted Stock Units  
Unvested, Beginning Balance | shares 635
Granted | shares 248
Vested | shares (224)
Forfeited | shares (45)
Unvested, Ending Balance | shares 614
Expected to vest at end of period | shares 589
Weighted Average Grant Date Fair Value  
Unvested, Beginning Balance | $ / shares $ 13.97
Granted | $ / shares 25.62
Vested | $ / shares 14.05
Forfeited | $ / shares 18.18
Unvested, Ending Balance | $ / shares 18.35
Expected to vest at end of period | $ / shares $ 18.13
Weighted Average Remaining Vesting Period (in years)  
Unvested at end of period 1 year 10 months 9 days
Expected to vest at end of period 1 year 10 months 9 days
Aggregate Intrinsic Value  
Unvested at end of period | $ $ 30,721 [1]
Expected to vest at end of period | $ $ 29,436 [1]
[1] The aggregate intrinsic value is calculated based on the fair value of $50.00 per share of the Company’s common stock on December 31, 2017 due to the fact that the restricted stock units carry a $0 purchase price.