Annual report pursuant to Section 13 and 15(d)

Shareholders' Equity, Stock Options and Net Income per Share - Employee Activity Non-vested Shares (Details)

v3.6.0.2
Shareholders' Equity, Stock Options and Net Income per Share - Employee Activity Non-vested Shares (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based compensation $ 8,334 $ 7,486 $ 6,681
Employee Non-vested Shares [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Share-based awards, vesting period 3 years    
Outstanding at beginning of year (shares) 191 190 186
Granted (shares) 134 100 99
Vested (shares) (94) (93) (94)
Forfeited (shares) (9) (6) (1)
Outstanding at end of year (shares) 222 191 190
Weighted average grant date fair value of non-vested shares at beginning of year $ 46 $ 40 $ 35
Weighted Average Grant Date Fair Value 44 51 42
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value 44 39 43
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value 45 45 37
Weighted average grant date fair value non-vested shares at end of year $ 45 $ 46 $ 40
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Granted in Period, Total Fair Value $ 10,108 $ 8,773 $ 7,585
Grant date fair value of shares that vested during the year 4,064 4,694 4,008
Share-based compensation 4,614 4,070 3,626
Tax benefit related to share-based compensation expense 1,712 $ 1,591 $ 1,385
Unrecognized compensation cost $ 5,900    
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition 1 year 9 months 11 days