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
9 Months Ended
Sep. 30, 2017
$ / shares
shares
Number of Unvested Restricted Shares  
Unvested shares as of January 1, 2017 (in shares) | shares 613,056
Granted (in shares) | shares 870,358
Vested (in shares) | shares (399,843)
Forfeited (in shares) | shares (74,024)
Unvested shares as of June 30, 2017 (in shares) | shares 1,009,547
Weighted Average Grant Date Fair Value  
Unvested shares as of January 1, 2017 (in dollar per share) | $ / shares $ 32.90
Granted (in dollars per share) | $ / shares 15.15
Vested (in dollars per share) | $ / shares 28.77
Forfeited (in dollars per share) | $ / shares 30.45
Unvested shares as of June 30, 2017 (in dollars per share) | $ / shares $ 19.42