Income Taxes - Tax Effects of Temporary Differences That Rises to Significant Portions of Deferred Tax Assets and Deferred Tax Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 1,249	$ 1,594
Allowance for doubtful accounts	3,288	3,156
Employee benefits and compensation	30,151	26,442
Lease costs	6,291	4,889
State tax credit carryforwards	1,291	1,322
Deferral of employer FICA taxes	3,983	0
Other deferred tax assets	424	30
Total gross deferred tax assets	46,677	37,433
Less: valuation allowance	(2,663)	(2,799)
Total deferred tax assets, net	44,014	34,634
Deferred tax liabilities:
Client list intangible assets	524	846
Goodwill and other intangibles	49,680	42,496
Property and equipment	2,071	2,291
Other deferred tax liabilities	491	721
Total gross deferred tax liabilities	52,766	46,354
Net deferred tax liability	$ (8,752)	$ (11,720)