Regulatory Matters (Regulatory Capital Levels And Related Ratios) (Details) $ in Thousands		Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (To Risk Weighted Assets), Ratio		12.50
Tier 1 Capital for Capital Adequacy (To Average Assets), Ratio		0.040
Common Equity Tier 1 Capital for Capital Adequacy (to Risk Weighted Assets), ratio		4.50%
Tier 1 Capital for Capital Adequacy (To Risk Weighted Assets), Ratio		0.060	0.040
Total Capital for Capital Adequacy (To Risk Weighted Assets), Ratio		0.080
Mid Penn Bancorp, Inc. [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital (To Average Assets)		$ 374,368	$ 188,501
Common Equity Tier 1 Capital (to Risk Weighted Assets)		365,084	188,501
Tier 1 Capital (To Risk Weighted Assets)		374,368	188,501
Total Capital (To Risk Weighted Assets)		$ 452,527	$ 246,529
Tier 1 Capital (to Average Assets), Ratio		0.081	0.068
Common Equity Tier 1 Capital (to Risk Weighted Assets), ratio		11.70%	9.60%
Tier 1 Capital (To Risk Weighted Assets), Ratio		0.120	0.096
Total Capital (To Risk Weighted Assets), Ratio		0.146	0.126
Tier 1 Capital for Capital Adequacy (To Average Assets)	[1]	$ 185,764	$ 111,201
Common Equity Tier 1 Capital for Capital Adequacy (to Risk Weighted Assets)	[1]	217,579	137,351
Tier 1 Capital for Capital Adequacy (To Risk Weighted Assets)	[1]	264,203	166,783
Total Capital for Capital Adequacy (To Risk Weighted Assets)	[1]	$ 326,369	$ 206,026
Tier 1 Capital for Capital Adequacy (To Average Assets), Ratio	[1]	0.040	0.040
Common Equity Tier 1 Capital for Capital Adequacy (to Risk Weighted Assets), ratio	[1]	7.00%	7.00%
Tier 1 Capital for Capital Adequacy (To Risk Weighted Assets), Ratio	[1]	0.085	0.085
Total Capital for Capital Adequacy (To Risk Weighted Assets), Ratio	[1]	0.105	0.105
Mid Penn Bank [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Capital (To Average Assets)		$ 398,773	$ 218,676
Common Equity Tier 1 Capital (to Risk Weighted Assets)		398,773	218,676
Tier 1 Capital (To Risk Weighted Assets)		398,773	218,676
Total Capital (To Risk Weighted Assets)		$ 413,442	$ 232,124
Tier 1 Capital (to Average Assets), Ratio		0.086	0.079
Common Equity Tier 1 Capital (to Risk Weighted Assets), ratio		12.80%	11.10%
Tier 1 Capital (To Risk Weighted Assets), Ratio		0.128	0.111
Total Capital (To Risk Weighted Assets), Ratio		0.133	0.118
Tier 1 Capital for Capital Adequacy (To Average Assets)	[1]	$ 185,721	$ 111,166
Common Equity Tier 1 Capital for Capital Adequacy (to Risk Weighted Assets)	[1]	217,446	137,288
Tier 1 Capital for Capital Adequacy (To Risk Weighted Assets)	[1]	264,041	166,707
Total Capital for Capital Adequacy (To Risk Weighted Assets)	[1]	$ 326,169	$ 205,933
Tier 1 Capital for Capital Adequacy (To Average Assets), Ratio	[1]	0.040	0.040
Common Equity Tier 1 Capital for Capital Adequacy (to Risk Weighted Assets), ratio	[1]	7.00%	7.00%
Tier 1 Capital for Capital Adequacy (To Risk Weighted Assets), Ratio	[1]	0.085	0.085
Total Capital for Capital Adequacy (To Risk Weighted Assets), Ratio	[1]	0.105	0.105
Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Average Assets)		$ 232,151	$ 138,958
Common Equity Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets)		201,914	127,482
Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets)		248,510	156,901
Total Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets)		$ 310,637	$ 196,126
Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Average Assets), Ratio		0.050	0.050
Common Equity Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets), ratio		6.50%	6.50%
Tier 1 Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets), Ratio		0.080	0.080
Total Capital to be Well-Capitalized Under Prompt Corrective Action Provision (To Risk Weighted Assets), Ratio		0.100	0.100

[1] The minimum amounts and ratios as of December 31, 2021 and December 31, 2020 include the full phase in of the capital conservation buffer of 2.5 percent required by the Basel III framework.