Capital Ratios (Narrative) (Details)		6 Months Ended
		Jun. 30, 2016		Dec. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Ratios, Basel III, Capital Conservation Buffer		0.625%
Future Capital Ratios Basel III Capital Conservation Buffer		2.50%
Adequately capitalized minimum ratios capital conservation buffer		0.625%
Farmers & Merchants Trust Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier 1 Risk-based Capital Ratio: Well Capitalized Minimum: Ratio	[1]	6.50%
Tier 1 Risk-based Capital Ratio: Well Capitalized Minimum: Ratio		8.00%	[2]	6.00%
Tier 1 Leverage Ratio: Well Capitalized Minimum: Ratio	[3]	5.00%
Total Risk-based Capital Ratio: Well Capitalized Minimum: Ratio	[4]	10.00%

[1] Common equity Tier 1 capital/ total risk-weighted assets

[2] Tier 1 capital / total risk-weighted assets

[3] Tier 1 capital / average quarterly assets

[4] Total risk-based capital / total risk-weighted assets