Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block]

The domestic and foreign components of income operations before income taxes and equity method investments were as follows (in thousands):

	Year Ended December 31,
	2021		2020		2019
Domestic	$	184,309	$	156,496	$	136,164
Foreign	(31)		(99)		(66)
Income from operations before income taxes and equity method investments	$	184,278	$	156,397	$	136,098

Schedule of Components of Income Tax Expense (Benefit) [Table Text Block]

The provision for income taxes was comprised of the following components (in thousands):

	Year Ended December 31,
	2021		2020		2019
Federal	$	18,513	$	16,296	$	(9,092)
State	9,770		7,463		6,015
Foreign	25		140		97
Current provision (benefit)	28,308		23,899		(2,980)
Federal	14,282		8,183		13,451
State	3,525		1,710		2,301
Deferred provision	17,807		9,893		15,752
Federal	1,312		1,996		9,440
State	141		87		—
Foreign	(27)		(10)		—
Non-current provision resulting from allocating tax benefits directly to changes in liabilities	1,426		2,073		9,440
Provision for income taxes	$	47,541	$	35,865	$	22,212

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

The schedule of effective income tax rate reconciliation is as follows:

	Year Ended December 31,
	2021		2020		2019
Statutory U.S. Federal tax rate	21.0	%	21.0	%	21.0	%
Increase (decrease) in tax rate resulting from:
State taxes—net of Federal benefit	5.8	%	4.9	%	4.8	%
Excess executive compensation	1.4	%	0.7	%	0.8	%
Research and development credit	(1.1)	%	(1.8)	%	(8.8)	%
Stock-based compensation	(1.1)	%	(0.9)	%	(1.3)	%
ESSP	(0.6)	%	(0.7)	%	(1.0)	%
Other, net	0.4	%	(0.3)	%	0.8	%
Effective tax rate	25.8	%	22.9	%	16.3	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

A summary of the tax effect of the significant components of deferred income taxes is as follows (in thousands):

	December 31,
	2021		2020
Goodwill and other intangibles	$	185,811	$	152,412
Property and equipment	22,585		17,237
Lease arrangements	18,676		25,863
Unbilled receivables - IRC Section 481(a)	—		2,946
Gross deferred tax liabilities	227,072		198,458
Retirement and other liabilities	(27,575)		(23,071)
Lease obligations	(21,717)		(28,652)
Allowance for potential contract losses and other contract reserves	(3,384)		(4,815)
Foreign and state operating loss carryforwards	(2,344)		(2,253)
Less: Valuation allowance	2,008		1,971
Gross deferred tax assets	(53,012)		(56,820)
Net deferred tax liabilities	$	174,060	$	141,638

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

A reconciliation of the beginning and ending balances of the total amounts of gross unrecognized tax benefits is as follows (in thousands):

	December 31,
	2021		2020		2019
Gross unrecognized tax benefits at beginning of year	$	11,708	$	9,635	$	490
Increases in tax positions for current year	1,562		1,712		1,839
Decreases in tax positions for prior years	(109)		—		(412)
Lapse in statute of limitations	(27)		(10)		—
Increases in tax positions for prior years	—		371		7,718
Gross unrecognized tax benefits at end of year	$	13,134	$	11,708	$	9,635