Income Taxes (Details) - USD ($)
|
9 Months Ended |
12 Months Ended |
|
Sep. 30, 2017 |
Sep. 30, 2015 |
Dec. 31, 2016 |
Dec. 31, 2012 |
Dec. 31, 2015 |
| Income Tax Examination [Line Items] |
|
|
|
|
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| Unrecognized Tax Benefits, Interest on Income Taxes Accrued |
$ (900,000)
|
|
$ (900,000)
|
|
$ 0
|
| Interest Expense related to unrecognized tax benefits |
0
|
|
(900,000)
|
|
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| Unrecognized Tax Benefits [Abstract] |
|
|
|
|
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| Unrecognized tax benefit - Permanent tax positions |
5,200,000
|
|
4,500,000
|
|
|
| Unrecognized tax benefit - Temporary tax positions |
5,100,000
|
|
24,200,000
|
|
|
| Total unrecognized tax benefit |
10,300,000
|
|
28,700,000
|
|
|
| NOL and tax credit carryforwards |
(5,800,000)
|
|
(5,900,000)
|
|
|
| Upper bound of decrease in unrecognized tax benefit that is reasonably possible |
7,000,000
|
|
|
|
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| Amounts accrued for penalties related to unrecognized tax benefits |
0
|
|
$ 0
|
|
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| Internal Revenue Service (IRS) |
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| Tax Audits [Abstract] |
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| Year(s) under examination |
|
2012 and 2013
|
|
2010 and 2011
|
|
| Year of carryback claim under examination |
|
|
|
2009
|
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| Potential Tax Adjustments |
$ 14,000,000
|
|
|
|
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| Earliest year subject to examination |
2009
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| State Jurisdiction (Texas) |
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| Tax Audits [Abstract] |
|
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| Year(s) under examination |
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|
2009 and 2010
|
|
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| Earliest year subject to examination |
2009
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