Operating Segments and Related Information (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue	$ 400,319	$ 358,141	$ 389,329	$ 348,583	$ 386,385	$ 332,230	$ 338,291	$ 348,452	$ 1,496,372	$ 1,405,358	$ 1,544,062
United States
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									755,640	717,841	803,423
Europe [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									370,800	337,163	382,388
Other Geographic Region [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenue									$ 369,932	$ 350,354	$ 358,251