Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation - Schedule of Modified Stock Options (Details)

v3.8.0.1
Stock-Based Compensation - Schedule of Modified Stock Options (Details)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2017
USD ($)
$ / shares
shares
Number of Shares (in thousands)  
Number of Shares, Outstanding, Beginning of Period (in shares) | shares 639,100
Number of Shares, Exercised (in shares) | shares (105,500)
Number of Shares, Outstanding, Ending of Period (in shares) | shares 533,600
Number of Shares, Exercisable (in shares) | shares 533,600
Weighted Average Exercise Price (per share)  
Outstanding, beginning of period (in dollars per share) | $ / shares $ 12.87
Exercised (in dollars per share) | $ / shares 13.41
Outstanding, end of period (in dollars per share) | $ / shares 12.77
Exercisable (in dollars per share) | $ / shares $ 12.77
Additional Stock Option Activity Disclosures  
Weighted Average Remaining Contractual Term (years), Outstanding 4 years 8 months
Weighted Average Remaining Contractual Term (years), Exercisable 4 years 8 months
Aggregate Intrinsic Value, Outstanding | $ $ 2.2
Aggregate Intrinsic Value, Exercisable | $ $ 2.2