Parent Company Financial Information, Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Balance Sheets [Abstract]
Investment Securities	$ 506,372	$ 430,533
Total Assets	2,922,121	2,615,345
Subordinated Debentures	10,310	10,310
Liabilities	2,642,140	2,363,510
Shareholders' Equity	279,981	251,835	$ 233,178	$ 209,904
Total Liabilities and Shareholders' Equity	2,922,121	2,615,345
Parent Company [Member]
Condensed Balance Sheets [Abstract]
Cash	228	308	$ 363	$ 416
Investment in Farmers & Merchants Bank of Central California	289,778	261,626
Investment Securities	409	409
Other Assets	184	60
Total Assets	290,599	262,403
Subordinated Debentures	10,310	10,310
Liabilities	308	258
Shareholders' Equity	279,981	251,835
Total Liabilities and Shareholders' Equity	$ 290,599	$ 262,403