|
Stock-Based Compensation (Summary of Activity Under Stock Option Plans) (Details) (USD $)
|
3 Months Ended |
12 Months Ended |
|
Mar. 31, 2015
|
Dec. 31, 2014
|
| Options Outstanding |
|
|
|
| Beginning Balance (shares) |
393,347 |
|
|
| Options granted (shares) |
0 |
|
|
| Options exercised (shares) |
(141,097) |
|
|
| Options forfeited (shares) |
(850) |
|
|
| Ending Balance (shares) |
251,400 |
|
393,347 |
| Options exercisable (shares) |
237,412 |
|
|
| Options vested or expected to vest (shares) |
250,980 |
[1] |
|
| Weighted- Average Exercise Price Per Share |
|
|
|
| Beginning Balance, Weighted-Average Exercise Price Per Share, (dollars per share) |
$ 40.72 |
|
|
| Options granted |
$ 0.00 |
|
|
| Options exercised |
$ 39.93 |
|
|
| Options forfeited |
$ 43.00 |
|
|
| Ending Balance, Weighted-Average Exercise Price Per Share, (dollars per share) |
$ 41.06 |
|
$ 40.72 |
| Options exercisable, Weighted-Average Exercise Price Per Share, (dollars per share) |
$ 40.42 |
|
|
| Options vested or expected to vest, Weighted-Average Exercise Price Per Share, (dollars per share) |
$ 41.05 |
[1] |
|
| Weighted-Average Remaining Contractual Life in Years |
|
|
|
| Options outstanding |
3 years 8 months |
|
3 years 9 months |
| Options exercisable, Weighted-Average Remaining Contractual Life in Years (years) |
3 years 4 months |
|
|
| Options vested or expected to vest, Weighted-Average Remaining Contractual Life in Years (years) |
3 years 8 months |
[1] |
|
| Aggregate Intrinsic Value |
|
|
|
| Options outstanding |
$ 10,344,139 |
|
$ 16,019,130 |
| Options exercisable, Aggregate Intrinsic Value |
9,920,540 |
|
|
| Options vested or expected to vest, Aggregate Intrinsic Value |
$ 10,331,431 |
[1] |
|
|
|
|