Incentive Award Plan - Narrative (Details)
$ in Millions |
|
|
3 Months Ended |
6 Months Ended |
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|
May 31, 2018
USD ($)
shares
|
May 01, 2018 |
Jun. 30, 2018
USD ($)
shares
|
Jun. 30, 2017
USD ($)
|
Jun. 30, 2018
USD ($)
shares
|
Jun. 30, 2017
USD ($)
|
Dec. 31, 2017
USD ($)
|
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Spin-off transaction, stock issuance ratio |
|
0.1
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| Unamortized stock-based compensation expense |
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|
$ 21.6
|
|
$ 21.6
|
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| General and administrative expense |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Stock-based compensation expense |
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|
$ 4.7
|
$ 9.2
|
9.1
|
$ 11.4
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| Non-vested Shares of Restricted Stock |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Deferred compensation expense |
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$ 7.9
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| Outstanding unvested shares | shares |
|
|
1,900,000
|
|
1,900,000
|
|
|
| Unamortized stock-based compensation expense |
|
|
$ 11.8
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$ 11.8
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| 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] |
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|
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| Grants in period (in shares) | shares |
|
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1,000,000
|
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| Performance Shares |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Minimum required service period |
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3 years
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| Number of shares available for grant | shares |
134,000
|
|
504,497
|
|
504,497
|
|
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| Dividend rights accrued |
|
|
$ 1.2
|
|
$ 1.2
|
|
$ 0.8
|
| Potential grants in period based on total shareholder return (in shares) | shares |
|
|
2,500,000
|
|
2,500,000
|
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|
| Unamortized stock-based compensation expense |
|
|
$ 9.8
|
|
$ 9.8
|
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| Performance Shares | Minimum |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
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| Multiplier for shares granted |
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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 |
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250.00%
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| Spirit MTA REIT | Spinoff | Non-vested Shares of Restricted Stock |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
|
|
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| Stock-based compensation expense accelerated due to spin-off |
$ 1.4
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