Basis of Presentation (Narrative) (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Jun. 05, 2019	Dec. 31, 2018
Common stock par value per share	$ 1.00		$ 1.00
Right-of-use asset	$ 3,605,000
Service cost	0
Accounting Standards Update 2016-02 [Member]
Operating lease liabilities			$ 4,400,000
Right-of-use asset			$ 4,000,000
Accounting Standards Update 2018-02 [Member]
Reclassification amount from accumulated other comprehensive income related to Tax Cuts and jobs Act	$ 471,000
DNB [Member]
Common stock par value per share		$ 1.00
S&T Bank [Member]
Business acquisition share price		1.22
Common stock par value per share		$ 2.50