XML 147 R119.htm IDEA: XBRL DOCUMENT v3.3.1.900
Share-based compensation Restricted Stock Units (Details) - Restricted stock units - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation, Restricted Shares [Roll Forward]      
Outstanding, beginning of period 261,235 288,151 315,094
Granted 85,772 117,786 111,231
Vested (102,173) (144,702) (118,885)
Forfeited (34,200) 0 (19,289)
Outstanding, end of period 210,634 261,235 288,151
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]      
Outstanding, beginning of period (in dollars per share) $ 25.77 $ 25.17 $ 22.82
Granted (in dollars per share) 33.69 25.17 26.88
Vested (in dollars per share) 25.67 24.09 20.48
Forfeited (in dollars per share) 27.09 0.00 25.62
Outstanding, end of period (in dollars per share) $ 28.82 $ 25.77 $ 25.17
Total weighted-average grant-date fair value $ 2.9 $ 3.0 $ 3.0