Operating Segments and Related Information (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010		Dec. 31, 2009
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 405,212	$ 371,327	[1]	$ 391,554	[1]	$ 375,969	[1]	$ 437,509	[1]	$ 332,497	$ 331,133	$ 287,298	$ 1,544,062	$ 1,388,437	[2]	$ 1,147,087
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue													803,423	734,748	[2]	672,270
Europe
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue													382,388	318,321	[2]	242,498
Other foreign
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue													$ 358,251	$ 335,368	[2]	$ 232,319

[1] Amounts for the fourth quarter of 2010 and the first three quarters of 2011 have been adjusted for the reclassification of certain discontinued operations to continuing operations.

[2] Amounts have been adjusted for the reclassification of certain discontinued operations to continuing operations.