Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details)

v3.3.1.900
Stock-Based Compensation (Summary of Restricted Stock Unit Activity) (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Restricted stock units outstanding, beginning, number of shares 658,760 674,494 641,116
Granted, number of shares 207,040 272,642 322,474
Vested, number of shares (243,765) (220,348) (232,714)
Forfeited, number of shares (68,746) (68,028) (56,382)
Restricted stock units outstanding, ending, number of shares 553,289 658,760 674,494
Restricted stock units outstanding, beginning, weighted average grate date fair value per share $ 31.03 $ 25.67 $ 24.16
Granted, weighted average grant date fair value per share 51.07 38.98 26.67
Vested, weighted average grant date fair value 28.09 25.21 23.04
Forfeited, weighted average grant date fair value 34.57 28.51 24.95
Restricted stock units outstanding, ending, weighted average grate date fair value per share $ 38.85 $ 31.03 $ 25.67