Pension and Profit Sharing - Pension Plan Assets by Fair Value Hiearchy (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension plan assets	$ 1,249,825	$ 1,294,727	$ 1,417,572
Money Market Fund
Pension plan assets	10,774	39,224
Equity Common and Collected Funds
Pension plan assets	836,594	837,260
Fixed Income Common and Collected Funds
Pension plan assets	402,431	418,243
Level 1
Pension plan assets	225,881	255,555
Level 1 | Money Market Fund
Pension plan assets		19,327
Level 1 | Equity Common and Collected Funds
Pension plan assets	125,451	131,737
Level 1 | Fixed Income Common and Collected Funds
Pension plan assets	100,430	104,491
Level 2
Pension plan assets	1,023,918	1,039,172
Level 2 | Money Market Fund
Pension plan assets	10,774	19,897
Level 2 | Equity Common and Collected Funds
Pension plan assets	711,143	705,523
Level 2 | Fixed Income Common and Collected Funds
Pension plan assets	302,001	313,752
Level 3
Pension plan assets	$ 0	$ 0