Share-based Compensation - Summary of Restricted Stock and Performance Unit Award Activity (Details)
|
9 Months Ended |
|
Sep. 30, 2016
$ / shares
shares
|
|---|
| Restricted Stock |
|
| Restricted stock and performance unit award activity (shares) [Roll Forward] |
|
| Outstanding at January 1, 2016 |
1,007,794
|
| Granted |
242,835
|
| Vested |
(417,544)
|
| Forfeitures |
(18,233)
|
| Outstanding at September 30, 2016 |
814,852
|
| Restricted stock and performance unit award activity (weighted average grant-date fair value) [Abstract] |
|
| Weighted average grant-date fair value of outstanding shares at January 1, 2016 | $ / shares |
$ 49.47
|
| Weighted average grant-date fair value of shares granted | $ / shares |
67.48
|
| Weighted average grant-date fair value of shares vested | $ / shares |
33.19
|
| Weighted average grant-date fair value of shares forfeitures | $ / shares |
58.72
|
| Weighted average grant-date fair value of outstanding shares at March 31, 2016 | $ / shares |
$ 62.98
|
| Performance Units |
|
| Restricted stock and performance unit award activity (shares) [Roll Forward] |
|
| Outstanding at January 1, 2016 |
175,675
|
| Granted |
77,017
|
| Vested |
(20,604)
|
| Forfeitures |
0
|
| Outstanding at September 30, 2016 |
232,088
|
| Restricted stock and performance unit award activity (weighted average grant-date fair value) [Abstract] |
|
| Weighted average grant-date fair value of outstanding shares at January 1, 2016 | $ / shares |
$ 59.94
|
| Weighted average grant-date fair value of shares granted | $ / shares |
67.57
|
| Weighted average grant-date fair value of shares vested | $ / shares |
57.58
|
| Weighted average grant-date fair value of shares forfeitures | $ / shares |
0.00
|
| Weighted average grant-date fair value of outstanding shares at March 31, 2016 | $ / shares |
$ 62.68
|
| Common stock issued upon vesting of award (in shares) |
21,111
|
| Common stock issued for dividends accrued (in shares) |
507
|