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Income Taxes (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Income Tax Disclosure [Abstract] |  |  |
Enactment of US Tax Reform |  | $ 2,500,000 |
Deferred tax liabilities |  |  |
Prepaid assets | $ (3,306,000) | (3,957,000) |
Depreciation | (3,918,000) | (2,021,000) |
Intangibles | (474,000) | 0 |
Software development costs | (4,950,000) | (3,732,000) |
Total deferred tax liabilities | (12,648,000) | (9,710,000) |
Deferred tax assets |  |  |
Accrued incentive compensation | 8,612,000 | 3,510,000 |
Net operating loss carryforward | 709,000 | 774,000 |
Workers’ compensation accruals | 4,739,000 | 4,586,000 |
Accrued rent | 918,000 | 676,000 |
Stock-based compensation | 6,183,000 | 4,233,000 |
Minority investment impairment | 676,000 | 667,000 |
Other | 305,000 | 216,000 |
Total deferred tax assets | 22,142,000 | 14,662,000 |
Valuation allowance | (678,000) | (669,000) |
Total net deferred tax assets | 21,464,000 | 13,993,000 |
Net deferred tax assets | 8,816,000 | 4,283,000 |
Current income tax expense |  |  |
Federal | 40,347,000 | 30,009,000 | $ 31,045,000
State | 11,133,000 | 5,988,000 | 5,190,000
Total current income tax expense | 51,480,000 | 35,997,000 | 36,235,000
Deferred income tax (benefit) expense |  |  |
Federal | (3,398,000) | 9,549,000 | 2,641,000
State | (1,135,000) | 193,000 | 310,000
Total deferred income tax (benefit) expense | (4,533,000) | 9,742,000 | 2,951,000
Total income tax expense | 46,947,000 | 45,739,000 | 39,186,000
Income tax benefit recognized related to Equity Compensation after adoption of ASU 2016-09, Quantification | $ 2,700,000 | $ 6,800,000 | $ 1,500,000
Reconciliation of income tax expense [Abstract] |  |  |
Assumed income tax rate (in hundredths) | 21.00% | 35.00% | 35.00%
Expected income tax expense at 21%, 35% and 35%, respectively | $ 38,296,000 | $ 45,549,000 | $ 36,812,000
State income taxes, net of federal benefit | 7,660,000 | 4,085,000 | 3,684,000
Nondeductible expenses | 4,831,000 | 2,649,000 | 1,669,000
Section 199 benefits | 0 | (875,000) | (686,000)
Equity compensation | (2,737,000) | (6,218,000) | (1,338,000)
Research and development credit | (856,000) | (634,000) | (751,000)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount | 0 | (669,000) | 0
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount | 0 | 2,559,000 | 0
Other, net | (247,000) | (707,000) | (204,000)
Total income tax expense | 46,947,000 | 45,739,000 | 39,186,000
Business Acquisition [Line Items] |  |  |
Liability for Uncertain Tax Positions, Current | 0 | $ 0 | $ 0
ExpensAble [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Operating Loss Carryforwards | $ 2,800,000 |  |
Minimum [Member] | ExpensAble [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Net operating loss carryforwards, expiration date | Jan. 01, 2023 |  |
Maximum [Member] | ExpensAble [Member] |  |  |
Business Acquisition [Line Items] |  |  |
Net operating loss carryforwards, expiration date | Jan. 01, 2030 |  |

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