Stock-based compensation - Narrative (Details) - USD ($)
$ / shares in Units, $ in Thousands |
12 Months Ended |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Compensation cost related to nonvested awards |
$ 10,214
|
$ 7,089
|
$ 7,207
|
| Dividends declared not paid on restricted stock units |
$ 238
|
$ 149
|
226
|
| 2016-LTIP Plan |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Number of shares available for issuable (in shares) |
2,240,434
|
2,377,574
|
|
| ESPP |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Number of shares reserved for issuance (in shares) |
2,379,006
|
2,409,185
|
|
| RSUs |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Fair value of restricted stock units vested and released |
$ 5,619
|
$ 9,923
|
$ 4,562
|
| Weighted average grant date fair value price of restricted stock granted (in USD per share) |
$ 31.35
|
$ 34.08
|
$ 39.55
|
| Compensation cost related to nonvested awards |
$ 9,213
|
$ 7,089
|
$ 7,436
|
| Awards granted (in shares) |
420,521,000
|
|
|
| Forfeitures (in shares) |
22,132,000
|
|
|
| Vesting (in shares) |
177,581,000
|
|
|
| RSUs | Independent Directors |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Compensation cost related to nonvested awards |
$ 898
|
724
|
$ 645
|
| Stock-Settled EBI Units and RSUs |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Unrecognized compensation cost related to nonvested awards |
$ 13,436
|
|
|
| Expected weighted-average period to be recognized |
2 years 6 months
|
|
|
| Dividends declared not paid on restricted stock units |
$ 613
|
$ 375
|
|
| PSUs |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Compensation cost related to nonvested awards |
1,001
|
|
|
| Unrecognized compensation cost related to nonvested awards |
$ 2,482
|
|
|
| Expected weighted-average period to be recognized |
2 years 1 month 6 days
|
|
|
| Criteria period |
3 years
|
|
|
| Vesting period |
3 years
|
|
|
| Awards granted (in shares) |
53,147
|
|
|
| Award vesting, percentage |
181.00%
|
|
|
| Forfeitures (in shares) |
0
|
|
|
| Vesting (in shares) |
0
|
|
|
| Employee Stock | ESPP |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Number of shares available for issuable (in shares) |
200,000
|
|
|
| Purchase price percentage of subsequent offering periods |
95.00%
|
|
|
| Maximum number of shares per participant (in shares) |
725
|
|
|
| Maximum worth of award per participant |
$ 25
|
|
|
| Shares issued under plan (in shares) |
30,179,000
|
23,171,000
|
|
| Minimum | PSUs |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Core return threshold percentages |
0.00%
|
|
|
| Maximum | PSUs |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Core return threshold percentages |
200.00%
|
|
|