Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation (Summary of Restricted Stock Award and Unit Activity) (Details)

v3.8.0.1
Stock-Based Compensation (Summary of Restricted Stock Award and Unit Activity) (Details) - Restricted Stock
3 Months Ended
Mar. 31, 2018
$ / shares
shares
Number of Unvested Restricted Shares  
Unvested shares as of January 1, 2018 (in shares) | shares 976,027
Granted (in shares) | shares 140,041
Vested (in shares) | shares (109,933)
Forfeited (in shares) | shares (5,937)
Unvested shares as of March 31, 2018 (in shares) | shares 1,000,198
Weighted Average Grant Date Fair Value  
Unvested shares as of January 1, 2018 (in dollar per share) | $ / shares $ 18.71
Granted (in dollars per share) | $ / shares 8.77
Vested (in dollars per share) | $ / shares 21.42
Forfeited (in dollars per share) | $ / shares 17.34
Unvested shares as of March 31, 2018 (in dollars per share) | $ / shares $ 17.03