Equity Compensation (Activity) (Details) - Stock options - $ / shares
|
|
12 Months Ended |
|
Jan. 01, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Jun. 11, 2013 |
| Shares Subject to Options Outstanding |
|
|
|
|
|
| Balance at the beginning of the period (in shares) |
1,081,212
|
2,069,802
|
3,776,405
|
4,572,672
|
|
| Granted (in shares) |
|
0
|
0
|
50,000
|
|
| Exercised (in shares) |
|
(979,586)
|
(1,617,659)
|
(685,798)
|
|
| Expired (in shares) |
|
(3,212)
|
(60,275)
|
(76,907)
|
|
| Forfeited (in shares) |
|
(5,792)
|
(28,669)
|
(83,562)
|
|
| Balance at the end of the period (in shares) |
|
1,081,212
|
2,069,802
|
3,776,405
|
|
| Exercisable options (in shares) |
|
1,031,239
|
|
|
|
| Vested and expected to vest at the end of the period (in shares) |
|
1,081,212
|
|
|
|
| Weighted Average Grant Date Fair Value |
|
|
|
|
|
| Granted (in dollars per share) |
|
|
|
$ 4.63
|
|
| Weighted Average Exercise Price |
|
|
|
|
|
| Balance at the beginning of the period (in dollars per share) |
$ 12.98
|
$ 12.13
|
$ 11.55
|
10.72
|
|
| Granted (in dollars per share) |
|
|
|
8.16
|
|
| Exercised (in dollars per share) |
|
11.20
|
10.48
|
5.01
|
|
| Expired (in dollars per share) |
|
5.95
|
17.51
|
14.96
|
|
| Forfeited (in dollars per share) |
|
13.30
|
16.70
|
14.81
|
|
| Balance at the end of the period (in dollars per share) |
|
12.98
|
$ 12.13
|
$ 11.55
|
|
| Exercisable options at the end of the period (in dollars per share) |
|
13.16
|
|
|
|
| Vested and expected to vest (in dollars per share) |
|
$ 12.98
|
|
|
|
| Weighted-Average Remaining Contractual Life |
|
|
|
|
|
| Exercisable options |
|
4 years 7 months 6 days
|
|
|
|
| Vested and expected to vest |
|
4 years 7 months 6 days
|
|
|
|
| 2013 Plan |
|
|
|
|
|
| Stock options |
|
|
|
|
|
| Potential annual increase in shares authorized for issuance as a percentage of shares outstanding as of the preceding December 31 |
|
|
|
|
5.00%
|
| Increase in number of shares authorized for issuance |
1,325,845
|
|
|
|
|