XML 92 R79.htm IDEA: XBRL DOCUMENT v3.19.2
Share-based compensation - Summary of changes in share based compensation (Details) - USD ($)
$ / shares in Units, $ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Restricted stock units        
Restricted stock awards and restricted stock units        
Outstanding, beginning of period (in shares) 211,225 208,088 200,358 197,047
Granted (in shares) 0 3,159 94,559 92,064
Vested (in shares) 0 (448) (76,712) (75,683)
Forfeited (in shares) (2,600) (9,943) (9,580) (12,572)
Outstanding, end of period (in shares) 208,625 200,856 208,625 200,856
Weighted-average grant-date fair value per share        
Outstanding, beginning of period (in dollars per share) $ 35.28 $ 32.97 $ 33.05 $ 31.53
Granted (in dollars per share) 0 33.78 37.68 34.09
Vested (in dollars per share) 0 31.94 32.61 30.56
Forfeited (in dollars per share) 35.56 32.05 33.82 32.27
Outstanding, end of period (in dollars per share) $ 35.28 $ 33.03 $ 35.28 $ 33.03
Total weighted-average grant-date fair value $ 0.0 $ 0.1 $ 3.6 $ 3.1
LTIP linked to TRS        
Restricted stock awards and restricted stock units        
Outstanding, beginning of period (in shares) 98,311 66,791 65,578 32,904
Granted (in shares) 0 1,315 34,647 36,941
Vested (in shares) 0 0 0 0
Forfeited (in shares) 0 (1,929) (1,914) (3,668)
Outstanding, end of period (in shares) 98,311 66,177 98,311 66,177
Weighted-average grant-date fair value per share        
Outstanding, beginning of period (in dollars per share) $ 39.61 $ 38.84 $ 38.81 $ 39.51
Granted (in dollars per share) 0 38.20 41.07 38.21
Vested (in dollars per share) 0 0 0 0
Forfeited (in dollars per share) 0 38.85 38.62 38.84
Outstanding, end of period (in dollars per share) $ 39.61 $ 38.82 $ 39.61 $ 38.82
Total weighted-average grant-date fair value $ 0.0 $ 0.1 $ 1.4 $ 1.4
LTIP awards linked to other performance conditions        
Restricted stock awards and restricted stock units        
Outstanding, beginning of period (in shares) 407,090 267,167 276,169 131,616
Granted (in shares) 0 5,257 138,580 147,766
Vested (in shares) 0 0 0 0
Forfeited (in shares) 0 (7,717) (7,659) (14,675)
Outstanding, end of period (in shares) 407,090 264,707 407,090 264,707
Weighted-average grant-date fair value per share        
Outstanding, beginning of period (in dollars per share) $ 35.12 $ 33.80 $ 33.80 $ 33.47
Granted (in dollars per share) 0 33.52 37.68 34.08
Vested (in dollars per share) 0 0 0 0
Forfeited (in dollars per share) 0 33.80 33.91 33.80
Outstanding, end of period (in dollars per share) $ 35.12 $ 33.79 $ 35.12 $ 33.79
Total weighted-average grant-date fair value $ 0.0 $ 0.2 $ 5.2 $ 5.0