Annual report pursuant to Section 13 and 15(d)

Stock Incentive Plans - Summary of Time-Based RSUs and Performance Stock Units (Details)

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Stock Incentive Plans - Summary of Time-Based RSUs and Performance Stock Units (Details)
shares in Thousands
12 Months Ended
Dec. 31, 2017
$ / shares
shares
2017 and 2007 Performance Incentive Plans | Time Based RSUs  
Shares  
Outstanding, beginning of period (in shares) | shares 82
Awarded (in shares) | shares 74
Forfeited (in shares) | shares (10)
Vested (in shares) | shares (44)
Outstanding, end of period (in shares) | shares 102
Weighted Average Grant-Date Fair Value (per share)  
Outstanding, beginning of period (in dollars per share) | $ / shares $ 61.16
Granted (in dollars per share) | $ / shares 53.13
Forfeited (in dollars per share) | $ / shares 56.38
Vested (in dollars per share) | $ / shares 57.21
Outstanding, end of period (in dollars per share) | $ / shares $ 57.51
2017 Stock Plan | Performance Stock Units  
Shares  
Outstanding, beginning of period (in shares) | shares 0
Awarded (in shares) | shares 30
Forfeited (in shares) | shares 0
Vested (in shares) | shares 0
Outstanding, end of period (in shares) | shares 30
Weighted Average Grant-Date Fair Value (per share)  
Outstanding, beginning of period (in dollars per share) | $ / shares $ 0.00
Granted (in dollars per share) | $ / shares 48.87
Forfeited (in dollars per share) | $ / shares 0.00
Vested (in dollars per share) | $ / shares 0.00
Outstanding, end of period (in dollars per share) | $ / shares $ 48.87