Defined Benefit Pension Plans Change in benefit obligation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 32,148	$ 28,251
Service cost	185	134	130
Interest cost	1,657	1,671	1,625
Actuarial loss	4,604	3,324
Settlements	(356)	0
Benefits paid	(2,193)	(1,232)
Projected benefit obligation at end of year	36,045	32,148	28,251
Accumulated benefit obligation at end of year	$ 35,790	$ 31,940