Right-Of-Use Assets and Lease Liabilities - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) director lease	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Lessee, Lease, Description [Line Items]
Number of lease contracts | lease	51
Number of operating lease agreements | lease	48
Number of financing leases | lease	3
Operating lease expense	$ 5,711	$ 4,221	$ 3,850
Number of operating leases considered abandoned | lease	2
Reduction of right-of-use asset value	$ 500
Right-of-use asset value after reduction	0
Reduction of operating lease liability	200
Expense recognized from lease abandonment	$ 300
Related party, lease with S&T Director
Lessee, Lease, Description [Line Items]
Number of directors | director	1
Operating lease expense	$ 200	200	$ 200
DNB
Lessee, Lease, Description [Line Items]
ROU asset acquired from DNB merger		$ 10,900