Stock Repurchase Program (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Feb. 29, 2004
Stock repurchase program
Stock Repurchased During Period, Value			$ 917,000
Announced stock repurchase program
Stock repurchase program
Shares authorized under repurchase program				250,000
Stock Repurchased During Period, Shares	32,900	60,000
Stock Repurchased During Period, Value	$ 2,100,000	$ 4,300,000
Other stock repurchase arrangements
Stock repurchase program
Stock Repurchased During Period, Shares	55,537	21,046	14,723
Stock Repurchased During Period, Value	$ 3,900,000	$ 1,400,000	$ 917,000