Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities
Prepaid assets	$ (4,252,000)	$ (3,306,000)
Depreciation	(4,564,000)	(3,918,000)
Software development costs	(6,475,000)	(4,950,000)
Deferred Tax Liabilities, Other	(3,209,000)	0
Deferred Tax Liabilities, Leasing Arrangements	(15,949,000)	0
Deferred Tax Liabilities, Goodwill and Intangible Assets	(955,000)	(474,000)
Total deferred tax liabilities	(35,404,000)	(12,648,000)
Deferred tax assets
Accrued incentive compensation	5,946,000	8,612,000
Net operating loss carryforward	632,000	709,000
Workers’ compensation accruals	5,404,000	4,739,000
Accrued rent	1,223,000	918,000
Stock-based compensation	6,712,000	6,183,000
DeferredTaxAssetsOperatingLeaseLiablities	19,158,000	0
Minority investment impairment	673,000	676,000
Other	287,000	305,000
Total deferred tax assets	40,035,000	22,142,000
Valuation allowance	(675,000)	(678,000)
Total net deferred tax assets	39,360,000	21,464,000
Net deferred tax assets	3,956,000	8,816,000
Current income tax expense
Federal	27,385,000	40,347,000	$ 30,009,000
State	6,299,000	11,133,000	5,988,000
Total current income tax expense	33,684,000	51,480,000	35,997,000
Deferred income tax (benefit) expense
Federal	4,016,000	(3,398,000)	9,549,000
State	844,000	(1,135,000)	193,000
Total deferred income tax (benefit) expense	4,860,000	(4,533,000)	9,742,000
Total income tax expense	38,544,000	46,947,000	45,739,000
Income tax benefit recognized related to Equity Compensation after adoption of ASU 2016-09, Quantification	$ 14,600,000	$ 3,900,000	$ 6,800,000
Reconciliation of income tax expense [Abstract]
Assumed income tax rate (in hundredths)	21.00%	35.00%	35.00%
Expected income tax expense at 21%, 21% and 35%, respectively	$ 39,825,000	$ 38,296,000	$ 45,549,000
State income taxes, net of federal benefit	5,821,000	7,660,000	4,085,000
Nondeductible expenses	5,959,000	4,831,000	2,649,000
Section 199 benefits	0	0	(875,000)
Equity compensation	(12,120,000)	(2,737,000)	(6,218,000)
Research and development credit	(1,069,000)	(856,000)	(634,000)
Effective Income Tax Rate Reconciliation, Tax Credit, Other, Amount	0	0	(669,000)
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount	0	0	2,559,000
Other, net	128,000	(247,000)	(707,000)
Total income tax expense	38,544,000	46,947,000	45,739,000
Liability for Uncertain Tax Positions, Current	0	$ 0	$ 0
ExpensAble [Member]
Operating Loss Carryforwards	$ 2,500,000