Other Assets, Net (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Assets held in Rabbi Trust	$ 39,418	$ 39,418		$ 36,164
Right-of-use assets for operating leases, net	$ 16,351	$ 16,351		16,835
Operating lease, right-of-use assets, financial statement location	Total Other assets, net	Total Other assets, net
Capitalized software, net	$ 15,243	$ 15,243		12,802
Equity method investment	15,779	15,779		10,488
Deferred loan costs, net	236	236		501
Other non-current assets	1,038	1,038		785
Total Other assets, net	88,065	88,065		77,575
Accumulated amortization of capitalized software	35,200	35,200		34,000
Loss on equity method investment		1,709	$ 1,237
Payments to acquire equity method investment		7,000	$ 2,500
WorkLLama
Schedule of Equity Method Investments [Line Items]
Ownership percentage					50.00%
Loss on equity method investment	$ 700	1,700
Payments to acquire equity method investment		$ 7,000		$ 4,000