Income taxes - Schedule of Significant Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Deferred compensation	$ 31,083	$ 24,782
Deferred rent and lease incentives	10,828	9,951
Net operating losses and credits	9,304	8,664
Receivable reserves	2,257	1,290
Accrued expenses	3,516	407
Auction rate securities reserves	1,387	1,366
Involuntary conversion	1,749	1,693
Other	986	1,010
Total deferred tax assets	61,110	49,163
Valuation allowance	(6,153)	(5,059)
Deferred tax assets after valuation allowance	54,957	44,104
Deferred tax liabilities:
Goodwill	42,455	41,128
Partnership investments	37,196	32,978
Company-owned life insurance	16,854	13,037
Depreciation	2,139	1,552
Other	329	318
Total deferred tax liabilities	98,973	89,013
Total deferred tax liabilities	$ (44,016)	$ (44,909)