Retirement Plans - Reconciliation of changes in projected benefit obligations (Details) (Pension Plans [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Pension Plans [Member]
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Accumulated benefit obligation at beginning of year	$ 7,109	$ 6,591
Interest cost	259	287	303
Actuarial (gain) loss	(738)	670
Expenses paid	(74)	(31)
Benefits paid	(406)	(408)
Accumulated benefit obligation at end of year	$ 6,150	$ 7,109	$ 6,591