Segment and Related Information (Reconciliation of Assets) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 1,211,189	$ 1,164,955	$ 1,116,100
Total Segments [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	972,500	959,600	926,200
Corporate [Member]
Segment Reporting, Asset Reconciling Item [Line Items]
Total assets	$ 238,700	$ 205,400	$ 189,900