Income Taxes - Internal Revenue Code and Adjustments - (Details) - USD ($) $ in Millions  | 
3 Months Ended | |
|---|---|---|
Mar. 31, 2019  | 
Mar. 31, 2018  | 
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| Income Taxes | ||
| Accrual of state income taxes, net of federal tax benefit | $ 0.5 | |
| Effective tax rate (as a percent) | 25.00% | 23.40% | 
| X | ||||||||||
- Definition Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
- References No definition available. 
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| X | ||||||||||
- Definition The amount of state income tax liability, net of federal tax benefit recorded as accrual. No definition available. 
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