Leases (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Summary of future minimum lease payments for operating leases
2012	$ 12,547
2013	11,135
2014	8,832
2015	7,472
2016	5,366
Thereafter	45,039
Total	90,391
Foreign [Member]
Summary of future minimum lease payments for operating leases
2012	1,836
2013	1,005
2014	789
2015	526
2016	268
Thereafter	167
Total	4,591
Domestic [Member]
Summary of future minimum lease payments for operating leases
2012	10,711
2013	10,130
2014	8,043
2015	6,946
2016	5,098
Thereafter	44,872
Total	$ 85,800