Employee Benefit and Deferred Compensation Plans - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Plan expense for noncontributory benefit pension plan and post-retirement health and life plans
Service cost	$ 0	$ 0	$ 0	$ 0
Interest cost	427	328	972	964
Expected return on plan assets	(618)	(539)	(1,639)	(1,617)
Prior service cost recognized	0	0	0	0
Recognized actuarial loss	88	59	244	150
Net periodic benefit cost (return)	(103)	(152)	(423)	(503)
Other Benefits
Plan expense for noncontributory benefit pension plan and post-retirement health and life plans
Service cost	5	1	13	13
Interest cost	15	19	45	65
Expected return on plan assets	0	0	0	0
Prior service cost recognized	0	0	0	0
Recognized actuarial loss	27	18	73	72
Net periodic benefit cost (return)	$ 47	$ 38	$ 131	$ 150