|
Equity Compensation (Details 3) (USD $)
|
3 Months Ended |
12 Months Ended |
|
Dec. 31, 2014
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
| Stock options |
|
|
|
|
| Total fair value for the awards vested during the period |
$ 800,000 |
$ 4,000,000 |
|
|
| Stock options |
|
|
|
|
| Intrinsic-value |
|
|
|
|
| Options Exercised |
|
22,668,000 |
1,315,000 |
1,310,000 |
| Options Exercisable |
22,718,000 |
22,718,000 |
42,116,000 |
16,800,000 |
| Options Vested and Expected to Vest |
$ 27,663,000 |
$ 27,663,000 |
$ 55,099,000 |
$ 25,773,000 |
| Assumptions used to estimate fair value of stock options |
|
|
|
|
| Expected volatility, minimum (as a percent) |
|
49.00% |
56.00% |
59.00% |
| Expected volatility, maximum (as a percent) |
|
60.00% |
59.00% |
63.00% |
| Expected dividends (as a percent) |
|
0.00% |
0.00% |
0.00% |
| Risk-free rate, minimum (as a percent) |
|
0.30% |
0.80% |
0.70% |
| Risk-free rate, maximum (as a percent) |
|
2.00% |
1.70% |
1.00% |
| Stock options | Minimum |
|
|
|
|
| Assumptions used to estimate fair value of stock options |
|
|
|
|
| Expected term |
|
1 year |
3 years 3 months 18 days |
5 years |
| Stock options | Maximum |
|
|
|
|
| Assumptions used to estimate fair value of stock options |
|
|
|
|
| Expected term |
|
6 years 1 month 6 days |
7 years 2 months 12 days |
6 years 1 month 6 days |