Lease Commitments for Leases having Terms of More than One Year (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012
Year-ended December 31:
2013	$ 102,469
2014	71,238
2015	42,076
2016	17,386
2017	11,937
Thereafter	18,285
Total	263,391
Property, Plant and Equipment
Year-ended December 31:
2013	13,930
2014	6,061
2015	894
2016	748
2017	629
Thereafter	5,170
Total	27,432
Rental Equipment
Year-ended December 31:
2013	88,539
2014	65,177
2015	41,182
2016	16,638
2017	11,308
Thereafter	13,115
Total	$ 235,959