Incentive Award Plan - Narrative (Details) - USD ($)
shares in Millions, $ in Millions |
3 Months Ended |
|
Mar. 31, 2017 |
Mar. 31, 2016 |
Dec. 31, 2016 |
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Unamortized stock-based compensation expense |
$ 21.7
|
|
|
| General and Administrative Expense |
|
|
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Stock-based compensation expense |
2.2
|
$ 2.3
|
|
| Non-vested Shares of Restricted Stock |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Deferred compensation expense |
$ 5.2
|
|
|
| Outstanding unvested shares (in shares) |
1.3
|
|
|
| Unamortized stock-based compensation expense |
$ 13.3
|
|
|
| Non-vested Shares of Restricted Stock | Executives Officers And Employees |
|
|
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Grants in period (in shares) |
0.5
|
|
|
| Performance Shares |
|
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Approved initial target grant (in shares) |
0.4
|
|
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| Minimum required service period (in years) |
3 years
|
|
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| Stock-based compensation expense |
$ 5.8
|
|
|
| Dividend rights accrued |
$ 0.8
|
|
$ 0.5
|
| Potential grants in period based on total shareholder return (in shares) |
0.3
|
|
|
| Unamortized stock-based compensation expense |
$ 8.4
|
|
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| Performance Shares | Minimum |
|
|
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
|
| Multiplier for shares granted (as a percent) |
0.00%
|
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| Performance Shares | Maximum |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
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| Multiplier for shares granted (as a percent) |
250.00%
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